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Published: 4 June 2021
Last updated: 20 February 2023

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1

Stone, G. C., U. Sjöbring, L. Björck, J. Sjöquist, C. V. Barber, and F. A. Nardella. "The Fc binding site for streptococcal protein G is in the C gamma 2-C gamma 3 interface region of IgG and is related to the sites that bind staphylococcal protein A and human rheumatoid factors." Journal of Immunology 143, no. 2 (July 15, 1989): 565–70. http://dx.doi.org/10.4049/jimmunol.143.2.565.

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Abstract The isolated 35 kDa fragment of protein G obtained by papain digestion of group G streptococci was found to bind solid phase intact IgG, Fc (2C gamma 2 + 2C gamma 3 domains), F(ab')2 and F(acb)2 (F(ab')2 + 2C gamma 2 domains) fragments but not pFc' (2C gamma 3 domains) fragments. The level of binding to rabbit F(acb)2 and rabbit F(ab')2 fragments was similar. Protein G binding to solid phase Fc fragments was inhibited by IgG, Fc, staphylococcal protein A and its monovalent fragment D, but was enhanced by F(ab')2 fragments. Chemical modification of tyrosine but not histidine residues of IgG abrogated its ability to inhibit the binding of protein G to solid phase Fc fragments. Protein G was found to strongly inhibit the binding of a monoclonal and a polyclonal human rheumatoid factor to IgG. These findings indicate that protein G binds with separate sites to the Fc and F(ab')2 fragments of IgG, that the interaction with the Fc fragment occurs at the C gamma 2-C gamma 3 domain interface region and that tyrosine but not histidine residues in this area are likely involved. The relationship of the Fc fragment-binding site specificity of protein G to that of other microbial IgG binding proteins and human rheumatoid factors is discussed.
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2

Diamond, B., L. Boccumini, and B. K. Birshtein. "Site of binding of IgG2b and IgG2a by mouse macrophage Fc receptors by using cyanogen bromide fragments." Journal of Immunology 134, no. 2 (February 1, 1985): 1080–83. http://dx.doi.org/10.4049/jimmunol.134.2.1080.

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Abstract Cyanogen bromide fragments of murine IgG2b and IgG2a immunoglobulins were used to localize the sequences that are bound by specific IgG2b and IgG2a Fc receptors on murine macrophages. One fragment from the CH2 domain of IgG2b bound to the gamma 2b Fc receptor. Two fragments from IgG2a--one one from the CH2 domain, differing by only four amino acids from the homologous IgG2b fragment, and the other from the CH3 domain--specifically bound to the gamma 2a Fc receptor. In both a rosetting assay and a radioactive binding assay, these two fragments from IgG2a competed with intact IgG2a: however, they did not compete with each other. Rather, binding of the fragment from the CH3 domain of IgG2a augmented the binding of the fragment from the CH2 domain of IgG2a but not that of the homologous fragment from IgG2b. The binding of both IgG2a fragments was abolished by trypsin treatment of macrophages. These data suggest that 1) a sequence in the CH2 domain of IgG2b is sufficient for binding to the gamma 2b Fc receptor, 2) sequences from both the CH2 and CH3 domains of IgG2a bind to the gamma 2a Fc receptor, and 3) the binding of sequences from the CH3 domain of IgG2a may induce a conformational change in the gamma 2a Fc receptor that leads to enhanced binding of sequences from the CH2 domain.
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3

Lee, B. W., C. F. Simmons, T. Wileman, and R. S. Geha. "Intracellular cleavage of newly synthesized low affinity Fc epsilon receptor (Fc epsilon R2) provides a second pathway for the generation of the 28-kDa soluble Fc epsilon R2 fragment." Journal of Immunology 142, no. 5 (March 1, 1989): 1614–20. http://dx.doi.org/10.4049/jimmunol.142.5.1614.

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Abstract It has been reported that the 45-kDa low affinity Fc epsilon R (Fc epsilon R2) on B cells is cleaved spontaneously from the cell surface to release a 28-kDa soluble fragment (sFc epsilon R2). This study demonstrates an additional mechanism by which B cells generate this fragment. Data from 35S methionine pulse-chase experiments with the Fc epsilon R2 bearing human B lymphoblastoid cell line, RPMI 8866, and immunoprecipitations of cell lysates and culture supernatants with an Fc epsilon R2 specific mAb, mAb 25, demonstrates the existence of a cell-associated 28-kDa Fc epsilon R2 fragment. This fragment was shown by partial amino(NH2)-terminal sequence analysis to be identical to the previously described 28-kDa sFc epsilon R2. The resistance to cell treatment with trypsin indicated that it was located intracellularly. Its appearance early in the biosynthesis of the Fc epsilon R2 (within a 10-min pulse), before the Fc epsilon R2 reached the cell surface, suggested that some of this fragment was generated intracellularly. Neutralization of acidic organelles with NH4Cl inhibited the formation of this intracellular fragment, strongly suggesting that it was a produce of intracellular cleavage of the Fc epsilon R2. Finally, this 28-kDa intracellular fragment was shown to be released into the culture supernatant, suggesting an intracellular mechanism by which the cells generate sFc epsilon R2.
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4

Willis, H. E., B. Browder, A. J. Feister, T. Mohanakumar, and S. Ruddy. "Monoclonal antibody to human IgG Fc receptors. Cross-linking of receptors induces lysosomal enzyme release and superoxide generation by neutrophils." Journal of Immunology 140, no. 1 (January 1, 1988): 234–39. http://dx.doi.org/10.4049/jimmunol.140.1.234.

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Abstract The monoclonal antibody KuFc79 binds to a determinant on the Fc receptors (Fc gamma R) of human leukocytes. We examined the biologic effects of the interaction of this antibody with Fc gamma R on human neutrophils (PMNL). The univalent Fab fragment of KuFc79 inhibits the formation of rosettes with IgG-sensitized sheep erythrocytes by as much as 91.7%. In other experiments in which PMNL were washed after exposure to Fab of KuFc79, phagocytosis of IgG-sensitized sheep erythrocytes was inhibited by 36%. Fab fragments of other mouse IgG2b monoclonal proteins did not have these effects. When PMNL are exposed to coverslips coated with univalent Fab fragments of this antibody, the Fc gamma R are removed from the surface of the PMNL. Under these conditions, rosetting could be inhibited by 85.4%. We examined cross-linking of receptor bound monoclonal antibody or its Fab fragment by either Protein A or F(ab')2 of an anti-mouse Ig. As much as 31.7% of beta-glucuronidase, a marker for lysosomal enzymes, is specifically released by cross-linking the Fc gamma R on PMNL. The generation of O2- is also induced by specifically cross-linking Fc gamma R with Fab and anti-Fab. The data constitute the first formal demonstration that cross-linking of Fc gamma R on PMNL leads to enzyme release and superoxide generation.
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5

di Tommaso, Anne, Matthieu O. Juste, Zineb Lakhrif, Marie-Noëlle Mévélec, Coraline Borowczyk, Pierre Hammeni, Guillaume Désoubeaux, et al. "Engineering and Functional Evaluation of Neutralizing Antibody Fragments Against Congenital Toxoplasmosis." Journal of Infectious Diseases 224, no. 4 (August 7, 2021): 705–14. http://dx.doi.org/10.1093/infdis/jiab141.

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Abstract Maternal-fetal transmission of Toxoplasma gondii tachyzoites acquired during pregnancy has potentially dramatic consequences for the fetus. Current reference-standard treatments are not specific to the parasite and can induce severe side effects. In order to provide treatments with a higher specificity against toxoplasmosis, we developed antibody fragments—single-chain fragment variable (scFv) and scFv fused with mouse immunoglobulin G2a crystallizable fragment (scFv-Fc)—directed against the major surface protein SAG1. After validating their capacity to inhibit T. gondii proliferation in vitro, the antibody fragments’ biological activity was assessed in vivo using a congenital toxoplasmosis mouse model. Dams were treated by systemic administration of antibody fragments and with prevention of maternal-fetal transmission being used as the parameter of efficacy. We observed that both antibody fragments prevented T. gondii dissemination and protected neonates, with the scFv-Fc format having better efficacy. These data provide a proof of concept for the use of antibody fragments as effective and specific treatment against congenital toxoplasmosis and provide promising leads.
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6

Carosella, E. D., A. B. Tilden, and N. E. Dunlap. "Human B cell differentiation by Fc fragment." Cellular Immunology 121, no. 2 (July 1989): 269–79. http://dx.doi.org/10.1016/0008-8749(89)90025-7.

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7

Coe, Alexander P. F., Janet A. Askari, Adam D. Kline, Martyn K. Robinson, Hishani Kirby, Paul E. Stephens, and Martin J. Humphries. "Generation of a Minimal α5β1Integrin-Fc Fragment." Journal of Biological Chemistry 276, no. 38 (June 1, 2001): 35854–66. http://dx.doi.org/10.1074/jbc.m103639200.

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8

Kim, Eunhee G., Jieun Jeong, Junghyeon Lee, Hyeryeon Jung, Minho Kim, Yi Zhao, Eugene C. Yi, and Kristine M. Kim. "Rapid Evaluation of Antibody Fragment Endocytosis for Antibody Fragment–Drug Conjugates." Biomolecules 10, no. 6 (June 25, 2020): 955. http://dx.doi.org/10.3390/biom10060955.

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Antibody–drug conjugates (ADCs) have emerged as the most promising strategy in targeted cancer treatment. Recent strategies for the optimization ADCs include the development of antibody fragment–drug conjugates (FDCs). The critical factor in the successful development of ADCs and FDCs is the identification of tumor antigen-specific and internalizing antibodies (Abs). However, systematic comparison or correlation studies of internalization rates with different antibody formats have not been reported previously. In this study, we generated a panel of scFv-phage Abs using phage display technology and their corresponding scFv and scFv-Fc fragments and evaluated their relative internalization kinetics in relation to their antibody forms. We found that the relative rates and levels of internalization of scFv-phage antibodies positively correlate with their scFv and scFv-Fc forms. Our systematic study demonstrates that endocytosis of scFv-phage can serve as a predictive indicator for the assessment of Ab fragment internalization. Additionally, the present study demonstrates that endocytic antibodies can be rapidly screened and selected from phage antibody libraries prior to the conversion of phage antibodies for the generation of the conventional antibody format. Our strategic approach for the identification and evaluation of endocytic antibodies would expedite the selection for optimal antibodies and antibody fragments and be broadly applicable to ADC and FDC development.
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9

Morgan, E. L., M. V. Hobbs, and W. O. Weigle. "Lymphocyte activation by the Fc region of immunoglobulin. I. Role of prostaglandins in the down regulation of Fc fragment-induced polyclonal antibody production." Journal of Immunology 134, no. 4 (April 1, 1985): 2247–53. http://dx.doi.org/10.4049/jimmunol.134.4.2247.

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Abstract Fc fragment-, subfragment-, and p23-induced polyclonal antibody production are regulated by endogenous and exogenous PGE. Addition of the PG synthetase inhibitor indomethacin (IM) to murine spleen cell cultures resulted in a significant increase in the amount of Ig secreted. Moreover, addition of exogenous PGE to culture resulted in a marked suppression of IgM and IgG secretion. Splenic adherent macrophages and P388D1 cells release PGE upon stimulation with Fc fragments, subfragments, and p23. The inclusion of IM or aspirin in culture was found to abrogate the ability of Fc fragments to induce PGE release from adherent cells. These results suggest a role for PG in immune complex mediated regulation of immune responses.
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10

Gallagher, D. Travis, Connor V. Galvin, and Ioannis Karageorgos. "Structure of the Fc fragment of the NIST reference antibody RM8671." Acta Crystallographica Section F Structural Biology Communications 74, no. 9 (August 29, 2018): 524–29. http://dx.doi.org/10.1107/s2053230x18009834.

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As the link between antigen binding and immune activation, the antibody Fc region has received extensive structural study. In this report, the structure of the Fc fragment of the NIST IgG1 mAb (reference material 8671) is described at 2.1 Å resolution in space group P212121, with approximate unit-cell parameters a = 50, b = 80, c = 138 Å. Prior Fc structures with a wide variety of modifications are also surveyed, focusing on those in the same crystal form. To facilitate the analysis of conformations, a reference frame and a two-parameter metric are proposed, considering the CH2 domains as mobile with respect to a fixed dimeric CH3 core. Over several human Fc structures, a significant variation in Fc elbow conformations is observed, which may serve to facilitate the regulation of Fc effector signaling.
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11

Smith, Tammy, Suzanne Liu, Noel Carlson, Stacey Clardy, and John Greenlee. "Neuronal Uptake of Paraneoplastic and Other IgGs is Mediated by the Fc Portion of the IgG Molecule and Involves Previously Uncharacterized Neuronal FcγRI Receptors: Implications for Antibody-Mediated Neuronal Injury." Neurology 99, no. 23 Supplement 2 (December 5, 2022): S66.2—S67. http://dx.doi.org/10.1212/01.wnl.0000903532.23948.76.

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ObjectiveTo investigate the mechanisms by which neurons take up paraneoplastic and other antibodies.BackgroundOur laboratory has previously demonstrated that neurons can take up both normal and paraneoplastic IgGs and that paraneoplastic autoantibodies such as anti-Yo and anti-Hu can bind to their intracellular target antigens to produce neuronal death. In this study we investigated how neuronal antibody uptake occurs.Design/MethodsWe first compared neuronal uptake of normal and paraneoplastic Fab fragments with that of normal IgG Fc fragments or whole paraneoplastic IgGs. To determine whether neurons expressed receptors capable of binding the Fc portion of the IgG molecule, paraformaldehyde-fixed mouse and rat brains sections were probed with antibodies for the three major types of Fc receptors: FcγRI (CD64), FcγRII, (CD32) and FcγRIII (CD16). Neuronal uptake of antineuronal IgGs was compared between wild type mice and knockout mice lacking the FcγRI receptor. We also investigated whether neuronal IgG uptake could be blocked by normal IgG.ResultsNeurons incorporated the Fc fragment of normal IgG but not the Fab fragment. Intact paraneoplastic IgGs were taken up by neurons, but immunospecific Fab fragments were excluded. Neurons throughout cerebrum, cerebellum, and brainstem showed immunolabeling for FcγRI, but only rare neurons expressed FcγRII or FcγRIII. Uptake of paraneoplastic IgG and neuronal death were not observed in cultures from FcγRI knockout mice but were extensive in cultures from wild type controls. Paraneoplastic antibody uptake could be inhibited by normal IgG.ConclusionsNeuronal uptake of normal and paraneoplastic IgGs requires the interaction of the Fc portion of the IgG molecule with previously uncharacterized neuronal FcγRI receptors. Our study provides a mechanism through which antibodies reactive with intracellular neuronal proteins could gain access to their target antigens to cause neuronal injury and neurological disease. The observation that neuronal antibody uptake can be blocked by normal IgG has possible implications for patient treatment.
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12

Jiang, Lei, Wei-Shan Chang, Hao Guo, Peng Sun, and Xiu-Mei Dai. "Structure analysis of goose immunoglobulin Y Fc fragment." Central European Journal of Immunology 3 (2013): 299–304. http://dx.doi.org/10.5114/ceji.2013.37745.

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13

Sawa, Yoshihiko, Tsuguo Watanabe, and Ken-ichiro Shibata. "Immunoglobulin G Fc Fragment-Binding Proteins inMycoplasma salivariumCells." Microbiology and Immunology 36, no. 6 (June 1992): 655–59. http://dx.doi.org/10.1111/j.1348-0421.1992.tb02067.x.

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14

Carosella, Edgardo D., Nicole Pascal, and Jacques Armand. "Fc fragment from human IgG induces PGE2 secretion." Cellular Immunology 121, no. 2 (July 1989): 261–68. http://dx.doi.org/10.1016/0008-8749(89)90024-5.

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15

Feige, Matthias J., Susanne Nath, Silvia R. Catharino, Daniel Weinfurtner, Stefan Steinbacher, and Johannes Buchner. "Structure of the Murine Unglycosylated IgG1 Fc Fragment." Journal of Molecular Biology 391, no. 3 (August 2009): 599–608. http://dx.doi.org/10.1016/j.jmb.2009.06.048.

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16

Sondermann, P., and V. Oosthuizen. "X-ray crystallographic studies of IgG-Fcγ receptor interactions." Biochemical Society Transactions 30, no. 4 (August 1, 2002): 481–86. http://dx.doi.org/10.1042/bst0300481.

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Human Fcγ receptors (FcγRs) for the Fc portion of IgG are major mediators of the adaptive immune response. Crystal structures of their extracellular domains were recently solved and shown to obey a common fold, resulting in a heart-shaped structure. Together with the multifunctional Fc fragment, whose structure was deciphered in the 1970s, the complex of an FcγR with Fc was recently crystallized. Its crystal structure indicates that despite the dimeric character of the Fc fragment, only one FcγR can bind to Fc, due to an introduced asymmetry within the homodimeric Fc, as well as by binding to symmetrically related residues of both Fc chains. Homology modelling suggested that the other FcγRs bind the Fc in a similar manner. The resolved complex structure can be regarded as a paradigm for Ig binding to Fc receptors and serves as a solid base for the design of compounds interfering with complex formation. Such molecules would be of invaluable benefit for the therapy of immunological disorders.
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17

Oppliger, I. R., F. A. Nardella, G. C. Stone, and M. Mannik. "Human rheumatoid factors bear the internal image of the Fc binding region of staphylococcal protein A." Journal of Experimental Medicine 166, no. 3 (September 1, 1987): 702–10. http://dx.doi.org/10.1084/jem.166.3.702.

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The binding specificity of rheumatoid factors (RFs) to human Fc resembles that of some microbial Fc-binding proteins, suggesting conformational similarities in their Fc-binding regions. Using polyclonal chicken antibodies against SPA, we have detected a crossreactive determinant shared by human RFs from different individuals, but not by non-RF IgM and IgG. Chicken anti-SPA was shown to bind to 18 of 19 IgM RFs and 2 of 2 IgG RFs isolated from different individuals. This binding was inhibitable with SPA, fragment D of SPA, human IgG, and Fc fragment of IgG. The binding site for RF was located on the Fab' fragment of chicken anti-SPA. The antigenic mimicry of RFs by a protein of microbial origin suggests that the immune response to infectious agents could induce or modulate RF production through an internal image autoantiidiotype mechanism.
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18

Chudzian, Julia, Anna Szlachcic, Malgorzata Zakrzewska, Miroslawa Czub, Marcin Pustula, Tad Holak, and Jacek Otlewski. "Specific Antibody Fragment Ligand Traps Blocking FGF1 Activity." International Journal of Molecular Sciences 19, no. 9 (August 21, 2018): 2470. http://dx.doi.org/10.3390/ijms19092470.

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Fibroblast growth factor 1 (FGF1) and its receptors (FGFRs) regulate crucial biological processes such as cell proliferation and differentiation. Aberrant activation of FGFRs by their ligands can promote tumor growth and angiogenesis in many tumor types, including lung or breast cancer. The development of FGF1-targeting molecules with potential implications for the therapy of FGF1-driven tumors is recently being considered a promising approach in the treatment of cancer. In this study we have used phage display selection to find scFv antibody fragments selectively binding FGF1 and preventing it from binding to its receptor. Three identified scFv clones were expressed and characterized with regard to their binding to FGF1 and ability to interfere with FGF1-induced signaling cascades activation. In the next step the scFvs were cloned to scFv-Fc format, as dimeric Fc fusions prove beneficial in prospective therapeutic application. As expected, scFvs-Fc exhibited significantly increased affinity towards FGF1. We observed strong antiproliferative activity of the scFvs and scFvs-Fc in the in vitro cell models. Presented antibody fragments serve as novel FGF1 inhibitors and can be further utilized as powerful tools to use in the studies on the selective cancer therapy.
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19

Rabasa Capote, Ailem, Jorge Ernesto González, Leyanis Rodríguez-Vera, Armando López, Belinda Sánchez Ramírez, and Greta Garrido Hidalgo. "Pharmacokinetics and Biodistribution Study of 7A7 Anti-Mouse Epidermal Growth Factor Receptor Monoclonal Antibody and Its Fragment in an Immunocompetent Mouse Model." ISRN Pharmacology 2012 (November 21, 2012): 1–8. http://dx.doi.org/10.5402/2012/417515.

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Immunocompetent mice, Fc receptor γ-chain deficient mice (), and molecular tools as F(ab′)2 bivalent fragments appear as the most suitable biological models to study the mechanisms of the action of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs). In vivo experiments contrasting antitumor effects of whole Abs and their bivalent fragments commonly involve a previous comparative pharmacokinetics study. In this paper, pharmacokinetics and biodistribution of an anti-mouse EGFR Ab were assessed using immunocompetent mice. 125I-labeled 7A7 mAb holds an elimination half-life () of 23.1 h in C57BL/6 mice. Accumulation of mAb was found in liver, spleen, kidneys, and mostly in lungs. We used an ELISA method to determine the of a 7A7 mAb using the same experimental setting. Results from this new analysis revealed a of 23.9 h, supporting this method as a safer and easier system to evaluate pharmacokinetics parameters of mAbs targeting mouse EGFR. Using this system we also studied pharmacokinetics of 7A7 F(ab′)2 fragment. A tenfold difference between the mAb and fragment was found. These data support the use of the 7A7 F(ab′)2 fragment in in vivo studies to explore the contribution of the EGFR signaling blockade and the Fc region to the antitumor effect of 7A7 mAb in this autologous scenario.
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20

Nardella, Francis A., and David C. Teller. "Fc intermediate (FcI), a papain-generated fragment of human IgG, intermediate in charge, molecular weight and cleavage between the Fc and Fc' fragments of IgG." Molecular Immunology 22, no. 6 (June 1985): 705–13. http://dx.doi.org/10.1016/0161-5890(85)90101-4.

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21

Rankin, B. M., S. A. Yocum, R. S. Mittler, and P. A. Kiener. "Stimulation of tyrosine phosphorylation and calcium mobilization by Fc gamma receptor cross-linking. Regulation by the phosphotyrosine phosphatase CD45." Journal of Immunology 150, no. 2 (January 15, 1993): 605–16. http://dx.doi.org/10.4049/jimmunol.150.2.605.

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Abstract The binding and subsequent cross-linking of murine IgG2a or human IgG to the Fc gamma R on the monocytic cell line THP-1 induced a rapid, dose-dependent increase in tyrosine phosphorylation of several proteins (a doublet centered around 110 kDa, and bands at 80, 60, and 52 kDa) and smaller increases in other proteins. This phosphorylation was accompanied by an increase in intracellular free Ca2+. The signaling required the cross-linking of the IgG, either through a biotin-avidin complex or with a F(ab')2 second antibody. Cross-linking of an F(ab')2 fragment of mAb 32.2 to Fc gamma RI (CD64) or an Fab fragment of mAb IV.3 to Fc gamma RII (CDw32) gave similar results to those observed with intact murine IgG2a or human IgG. Cross-linking of a F(ab')2 fragment of mAb 3G8 to Fc gamma RIII (CD16) had very little effect. Increases in both tyrosine phosphorylation and intracellular free Ca2+ were significantly reduced in a dose-dependent manner upon treatment of THP-1 cells with the tyrosine kinase inhibitors herbimycin-A, genistein, or erbstatin. Additionally, there was a marked inhibition of both Ca2+ mobilization and tyrosine phosphorylation when a F(ab')2 fragment of a mAb (T191) to the protein tyrosine phosphatase CD45, was co-cross-linked with either Hu-IgG, Mu-IgG2a, F(ab')2 anti-Fc gamma RI, or Fab anti-Fc gamma RII. Taken together these results suggest that signaling through Fc gamma RI (CD64) and Fc gamma RII (CDw32) in the monocytic leukemia cell line THP-1 gives rise to rapid tyrosine phosphorylation of several proteins followed by an increase in intracellular calcium. In addition, CD45 is able to inhibit the intracellular signaling when it is brought into close proximity to the Fc gamma R. This suggests that this transmembrane tyrosine phosphatase may regulate the stimulation of the cells through the Fc gamma R.
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22

Hoffmeyer, F., K. Witte, U. Gebhardt, and R. E. Schmidt. "The low affinity Fc gamma RIIa and Fc gamma RIIIb on polymorphonuclear neutrophils are differentially regulated by CD45 phosphatase." Journal of Immunology 155, no. 8 (October 15, 1995): 4016–23. http://dx.doi.org/10.4049/jimmunol.155.8.4016.

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Abstract Stimulation of human polymorphonuclear neutrophils through ligation and cross-linking of the low affinity Fc gamma RIIa and Fc gamma RIIIb using mAb Fab and F(ab')2 fragments led to transient intracellular calcium mobilization and activation of the respiratory burst. Fc gamma RIIIb engagement resulted in a different pattern of intracellular calcium flux, and induction of the respiratory burst was significantly more effective than in the case of Fc gamma RIIa. These data demonstrate that the capacity of Fc gamma RIIIb to transduce transmembrane signals itself contributes to full cell activation. Treatment with a mAb F(ab')2 fragment recognizing CD45 phosphatase suppressed Fc gamma R-induced calcium mobilization in a dose-dependent manner. An ongoing intracellular calcium mobilization was immediately terminated when activation was followed by co-cross-linking Fc gamma R and CD45. This suggests that the initial steps of Fc gamma R signal transduction pathways are influenced by the state of tyrosine phosphorylation. Combined cross-linking of both receptors, however, was hardly susceptible to CD45. Also, inhibition of respiratory burst by CD45 in the case of Fc gamma RIIIb was minimal compared with that for Fc gamma RIIa. Signal transduction pathways of low affinity Fc gamma RIIa and Fc gamma RIIIb are differentially regulated by CD45, underlining the essential function of Fc gamma R-mediated tyrosine phosphorylation in polymorphonuclear neutrophil activation.
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23

Goroff, D. K., and F. D. Finkelman. "Activation of B cells in vivo by a Fab/Fc fragment of a monoclonal anti-IgD antibody requires an interaction between the antibody fragment and a cellular IgG Fc receptor." Journal of Immunology 140, no. 9 (May 1, 1988): 2919–24. http://dx.doi.org/10.4049/jimmunol.140.9.2919.

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Abstract To investigate activation of B lymphocytes in vivo by an interaction between B cell surface Ig (sIg) and an anti-Ig antibody, we compared the abilities of a divalent IgG2b anti-IgD mAb, H delta a/1, and its univalent Fab/Fc fragment to enhance B cell sIa expression in vivo. The Fab/Fc fragment consists of a single Fab linked to Fc, and can interact with C and cellular Fc receptors. Although injection of BALB/c mice with either intact H delta a/1 or H delta a/1 Fab/Fc enhanced splenic B cell sIa expression, Ia expression was enhanced more by intact H delta a/1. Furthermore, injection of mice with 24G2, a mAb to the B cell and macrophage IgG2b Fc receptor, completely blocked the ability of 20 to 500 micrograms of H delta a/1 Fab/Fc to enhance B cell sIa expression, but had no effect on enhancement of B cell sIa expression by 100 micrograms of intact H delta a/1. This effect of 24G2 was mediated by its blocking of IgG2b receptor function rather than simply by its binding to B lymphocytes, since a mAb to the B cell IgE receptor did not interfere with the ability of H delta a/1 Fab/Fc to enhance B cell sIa expression. The different effects of 24G2 on B cell activation by intact H delta a/1 and H delta a/1 Fab/Fc were not a result of differences in the abilities of the intact antibody and its Fab/Fc fragment to activate B cells, since 24G2 did not interfere with the ability of AMS-15, a IgG2a anti-IgD mAb, to slightly increase B cell sIa expression. These observations indicate that a univalent ligand for B cell sIg can activate B lymphocytes in vivo through an IgGFc-IgGFc receptor-dependent interaction.
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24

Conrad, D. H., A. D. Keegan, K. R. Kalli, R. Van Dusen, M. Rao, and A. D. Levine. "Superinduction of low affinity IgE receptors on murine B lymphocytes by lipopolysaccharide and IL-4." Journal of Immunology 141, no. 4 (August 15, 1988): 1091–97. http://dx.doi.org/10.4049/jimmunol.141.4.1091.

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Abstract Recent work in both the human and murine systems has demonstrated that IL-4 is capable of specifically inducing the synthesis of the low affinity receptor for IgE (Fc epsilon RII). In addition, in conjunction with LPS, IL-4 will induce IgG1 and IgE synthesis. To analyze the correlation between Fc epsilon RII induction and IgE secretion, Fc epsilon RII and IgE levels were measured by RIA on murine splenic B cells stimulated with LPS and IL-4 over 7 days of culture. Treatment with LPS and IL-4 gave a 20- to 50-fold (day 3) "superinduction" of Fc epsilon RII levels compared with a 3- to 5-fold induction with IL-4 alone; removal of IL-4 resulted in a rapid decline in Fc epsilon RII levels. The cells expressing high Fc epsilon RII levels were determined to be blasts. Superinduction of Fc epsilon RII occurs at 10 U/ml IL-4 and remains relatively constant in the range of 10 to 1000 U/ml. In contrast, with increasing IL-4, IgE levels increase, reaching microgram levels at day 7 with 300 U/ml IL-4. Triggering the cells with anti-Ig, as expected, gave no Ig secretion, and in addition, Fc epsilon RII superinduction by IL-4 and anti-Ig was not seen. PMA is known to block Ig secretion induced by LPS. Concentrations of PMA that totally abrogated IgE secretion had no effect on Fc epsilon RII superinduction, indicating that the latter phenomena can be separated from IL-4-induced Ig secretion. Superinduction also results in higher levels of Fc epsilon RII fragment release into the media. Thus, attempts were made to influence IgE secretion by adding additional purified Fc epsilon RII fragment to the culture. The purified fragment did not have a significant influence on IgE levels in this system.
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25

Richards, M. L., and D. H. Katz. "Regulation of the murine Fc epsilon RII (CD23) gene. Functional characterization of an IL-4 enhancer element." Journal of Immunology 152, no. 7 (April 1, 1994): 3453–66. http://dx.doi.org/10.4049/jimmunol.152.7.3453.

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Abstract The murine B cell IgE receptor (Fc epsilon RII, CD23) has been implicated in various functions including IgE regulation, Ag presentation, and B cell differentiation/activation. We have undertaken a series of studies to identify promoter sequences that are important for the constitutive and IL-4-induced expression of the murine Fc epsilon RII in M12.4.5 B lymphoma cells. By use of RNase protection analysis it was established that murine splenic B cells and M12.4.5 cells predominantly express the Fc epsilon RIIa form and that this receptor subtype accounts for the vast majority of IL-4-induced Fc epsilon RII mRNA in B cells. A 101-bp segment of the murine Fc epsilon RII proximal promoter coupled to a heterologous SV40 promoter was found to impart IL-4 inducibility in reporter assays. Removal of either 10 bp from the 5' end or 17 bp from the 3' end of this 101-bp fragment substantially reduced the IL-4 response. Both of these terminal deletions removed sequences that share homology with established IL-4 response elements of MHC class II and Ig (gamma 1 and epsilon) heavy chain genes. In addition, near the center of this 101-bp fragment lies a sequence that is highly homologous with NF-kappa B/LPS response elements previously identified upstream of the A alpha gene. DNA fragments containing this sequence together with one of the putative IL-4 response elements were able to impart a small LPS/IL-4 response in M12.4.5 cells. These results suggest that IL-4 and LPS induction of murine B cell Fc epsilon RII expression is mediated by a complex of transcription factors.
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26

Fan, Qing, Huawei Cai, Hao Yang, Lin Li, Cen Yuan, Xiaofeng Lu, and Lin Wan. "Biological Evaluation of131I- and CF750-Labeled Dmab(scFv)-Fc Antibodies for Xenograft Imaging of CD25-Positive Tumors." BioMed Research International 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/459676.

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A Dmab(scFv)-Fc antibody containing the single chain variable fragment of a humanized daclizumab antibody and the Fc fragment of a human IgG1 antibody was produced via recombinant expression inPichia pastoris. The Dmab(scFv)-Fc antibody forms a dimer in solution, and it specifically binds CD25-positive tumor cells and tumor tissues. For tumor imaging, the Dmab(scFv)-Fc antibody was labeled with the 131I isotope and CF750 fluorescent dye, respectively. After intravenous injection of mice bearing CD25-positive tumor xenografts, tumor uptake of the131I-Dmab(scFv)-Fc antibody was visible at 1 h, and clear images were obtained at 5 h using SPECT/CT. After systemic administration of the CF750-Dmab(scFv)-Fc antibody, tumor uptake was present as early as 1 h, and tumor xenografts could be kinetically imaged within 9 h after injection. These results indicate that the Dmab(scFv)-Fc antibody rapidly and specifically targets CD25-positive tumor cells, suggesting the potential of this antibody as an imaging agent for the diagnosis of lymphomatous-type ATLL.
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27

Rao, M., W. T. Lee, and D. H. Conrad. "Characterization of a monoclonal antibody directed against the murine B lymphocyte receptor for IgE." Journal of Immunology 138, no. 6 (March 15, 1987): 1845–51. http://dx.doi.org/10.4049/jimmunol.138.6.1845.

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Abstract A rat hybridoma producing a high-affinity IgG2a monoclonal antibody (B3B4) directed against against the murine lymphocyte IgE receptor (Fc epsilon R) was established by using purified Fc epsilon R from Fc epsilon R+ murine hybridoma B cells as immunogen. The monoclonal and polyclonal anti-Fc epsilon R inhibited the binding of IgE to the murine lymphocyte Fc epsilon R and were also used to isolate the Fc epsilon R. B3B4 specifically recognized only the 49-Kd Fc epsilon R on murine B lymphocyte as determined by immunoprecipitation and SDS-PAGE analysis. In addition to its reaction with intact Fc epsilon R, B3B4 also recognized Fc epsilon R fragments that were present in the culture media of Fc epsilon R+ hybridoma cells. The predominant fragments isolated were 38 Kd and 28 Kd by SDS-PAGE analysis. When tested for reactivity with other cell types, B3B4 was highly specific for murine B lineage cells in that it did not significantly react with Fc epsilon R on macrophages and T cells and, in addition, did not react with the high affinity mast cell Fc epsilon R. B3B4 completely blocked IgE rosetting, and a reciprocal inhibition of binding was seen in a dose-dependent fashion between IgE and B3B4, indicating a close proximity of the IgE and B3B4 binding sites. Saturation binding analysis indicated that the Fab' fragment of B3B4 bound to twice as many sites/cell as IgE, suggesting that there are two identical B3B4 determinants per 49-Kd Fc epsilon R or that the IgE binding site is formed by the association of at least two 49-Kd Fc epsilon R. However, unlike IgE, neither B3B4 nor F(ab')2-B3B4 nor Fab'-B3B4 were very effective in causing Fc epsilon R upregulation on murine hybridoma B cells; in fact, B3B4 prevented this upregulation when added in combination with IgE. These results suggest that a site-specific interaction provided only by IgE may be essential for ligand-specific upregulation. Both polyclonal and monoclonal antibodies will be useful in further studies concerning the functional relationship between the membrane Fc epsilon R and the soluble Fc epsilon R fragments.
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28

Penha, Tânia Regina, Ernesto Renato Krüger, Vanete Thomaz-Soccol, Jorge Victor Bacila Agottani, Flávio Hiroshi Itano, Ludmilla Della Coletta Troiano, and Josiane Brodzinski. "Production and characterization of monoclonal antibodies anti fragment Fc of bovine IgG." Brazilian Archives of Biology and Technology 53, no. 1 (February 2010): 105–14. http://dx.doi.org/10.1590/s1516-89132010000100014.

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The aim of this work was to produce and characterize monoclonal antibodies anti bovine immunoglobulin G (IgG). Out of seven hybridomas, two were chosen based on the ELISA'S absorbance values and were labeled B4F11 and B3H12. These monoclonals were analyzed through Western Blot for IgG fragments obtained by proteolysis with papain, separated by electrophoresis in polyacrylamide gel electrophoresis with β-mercaptoetanol as reducing agent. This revealed that, possibly, the B4F11 was directed to a conformational antigen, and that B3H12 reacted in a specific fashion with Fc (Bovine IgG crystallizable fragment). This antibody could be used in the development of reagents to immunoassays relevant for research and diagnosis.
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29

Dolhofer-Bliesener, R., and K. D. Gerbitz. "Impairment by glycation of immunoglobulin G Fc fragment function." Scandinavian Journal of Clinical and Laboratory Investigation 50, no. 7 (January 1990): 739–46. http://dx.doi.org/10.3109/00365519009091067.

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30

Carosella, Edgardo D., Chantal Gay, Jacques Armand, and Jean-Louis Touraine. "Human B-cell differentiation by Fc fragment of IgG." Cellular Immunology 112, no. 2 (April 1988): 262–70. http://dx.doi.org/10.1016/0008-8749(88)90296-1.

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31

Lobner, Elisabeth, Michael W. Traxlmayr, Christian Obinger, and Christoph Hasenhindl. "Engineered IgG1‐Fc – one fragment to bind them all." Immunological Reviews 270, no. 1 (February 10, 2016): 113–31. http://dx.doi.org/10.1111/imr.12385.

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32

CHRISTENSEN, POUL, BENGT G. JOHANSSON, and GORAN KRONVALL. "INTERACTION OF STREPTOCOCCI WITH THE Fc FRAGMENT OF IgG." Acta Pathologica Microbiologica Scandinavica Section C Immunology 84C, no. 2 (August 15, 2009): 73–76. http://dx.doi.org/10.1111/j.1699-0463.1976.tb00001.x.

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33

Taubitz, Tatjana, Laura-Pia Steinbrenner, Alexander V. Tschulakow, Antje Biesemeier, Sylvie Julien-Schraermeyer, and Ulrich Schraermeyer. "Effects of intravitreally injected Fc fragment on rat eyes." Graefe's Archive for Clinical and Experimental Ophthalmology 254, no. 12 (October 17, 2016): 2401–9. http://dx.doi.org/10.1007/s00417-016-3511-y.

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34

Siddiqui, Sonia, Andrea Horvat-Bröcker, and Andreas Faissner. "The glia-derived extracellular matrix glycoprotein tenascin-C promotes embryonic and postnatal retina axon outgrowth via the alternatively spliced fibronectin type III domain TNfnD." Neuron Glia Biology 4, no. 4 (November 2008): 271–83. http://dx.doi.org/10.1017/s1740925x09990020.

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Tenascin-C (Tnc) is an astrocytic multifunctional extracellular matrix (ECM) glycoprotein that potentially promotes or inhibits neurite outgrowth. To investigate its possible functions for retinal development, explants from embryonic day 18 (E18) rat retinas were cultivated on culture substrates composed of poly-d-lysine (PDL), or PDL additionally coated with Tnc or laminin (LN)-1, which significantly increased fiber length. When combined with LN, Tnc induced axon fasciculation that reduced the apparent number of outgrowing fibers. In order to circumscribe the stimulatory region, Tnc-derived fibronectin type III (TNfn) domains fused to the human Ig-Fc-fragment TNfnD6-Fc, TNfnBD-Fc, TNFnA1A2-Fc and TNfnA1D-Fc were studied. The fusion proteins TNfnBD-Fc and to a lesser degree TNfnA1D-Fc were stimulatory when compared with the Ig-Fc-fragment protein without insert. In contrast, the combination TNfnA1A2-Fc reduced fiber outgrowth beneath the values obtained for the Ig-Fc domain, indicating potential inhibitory properties. The monoclonal J1/tn2 antibody (clone 578) that is specific for domain TNfnD blocked the stimulatory properties of the TNfn-Fc fusions. When postnatal day 7 retinal ganglion cells were used rather that explants, Tnc and Tnc-derived proteins proved permissive for neurite outgrowth. The present study highlights a strong retinal axon growth-promoting activity of the Tnc domain TNfnD, which is modulated by neighboring domains.
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35

Ukkonen, P., V. Lewis, M. Marsh, A. Helenius, and I. Mellman. "Transport of macrophage Fc receptors and Fc receptor-bound ligands to lysosomes." Journal of Experimental Medicine 163, no. 4 (April 1, 1986): 952–71. http://dx.doi.org/10.1084/jem.163.4.952.

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Mouse macrophage Fc receptors specific for IgG1/IgG2b mediate the binding and pinocytic uptake of soluble IgG-containing antibody-antigen complexes. Internalization of these multivalent IgG complexes is accompanied not only by the intracellular degradation of the ligand, but also by a net decrease in the number of plasma membrane Fc receptors and an accelerated rate of receptor turnover. In contrast, internalized receptors bound to a monovalent ligand, the high affinity Fab fragment of the antireceptor mAb 2.4G2, escape degradation by rapidly recycling to the cell surface. In this paper, we have characterized the intracellular pathway involved in the endocytosis and transport of Fc receptors in the J774 macrophage cell line. The results show that the uptake of multivalent ligands follows the normal pathway of receptor-mediated endocytosis: internalization in clathrin-coated pits and coated vesicles, delivery to endosomes, and finally to acid hydrolase-rich lysosomes. Immunoprecipitation of radiolabeled receptor from Percoll density gradients showed that endocytosis of the IgG complexes also results in the concomitant transport of the receptor to lysosomes. Although uptake of the monovalent Fab fragment had no detectable effect on intracellular receptor distribution, preparations of 2.4G2 Fab rendered multivalent by adsorption to colloidal gold were as effective as the IgG complexes at causing lysosomal accumulation of internalized receptors. Thus, it is likely that the down-regulation and degradation of Fc receptors which occurs during the endocytosis of antibody-antigen complexes is due to the transport of internalized receptors to lysosomes. Moreover, the ability of certain Fc receptor-bound ligands to interfere with receptor recycling and trigger lysosomal transport seems to depend on ligand valency rather than on the presence or absence of Fc domains on intact IgG molecules.
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36

Shen, Hong, Manna Zhang, Kelly Kaita, Gerald Y. Minuk, Julia Rempel, and Yuewen Gong. "Expression of Fc Fragment Receptors of Immunoglobulin G (Fc?Rs) in Rat Hepatic Stellate Cells." Digestive Diseases and Sciences 50, no. 1 (January 2005): 181–87. http://dx.doi.org/10.1007/s10620-005-1298-5.

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37

Kolenko, Petr, Tereza Skálová, Jan Dohnálek, and Jindřich Hašek. "L-Fucose in Crystal Structures of IgG-Fc: Reinterpretation of Experimental Data." Collection of Czechoslovak Chemical Communications 73, no. 5 (2008): 608–15. http://dx.doi.org/10.1135/cccc20080608.

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Glycosylation of IgG-Fc plays an important role in the activation of the immune system response. Effector functions are modulated by different degrees of deglycosylation of IgG-Fc. However, the geometry of oligosaccharides covalently bound to IgG-Fc does not seem to be in good agreement with electron density in most of the structures deposited in the Protein Data Bank. Our study of correlation between the oligosaccharide geometry, connectivity, and electron density shows several discrepancies, mainly for L-fucose. Revision of refinement of two structures containing the Fc-fragment solved at the highest resolution brings clear evidence for α-L-fucosylation instead of β-L-fucosylation as it was claimed in most of the deposited structures in the Protein Data Bank containing the Fc-fragment, and also in the original structures selected for re-refinement. Our revision refinement results in a decrease in R factors, better agreement with electron density, meaningful contacts, and acceptable geometry of L-fucose.
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38

Zhuang, Zhiqiang, Zhe Wang, Kewen Wang, and James Delgrande. "A Generalisation of AGM Contraction and Revision to Fragments of First-Order Logic." Journal of Artificial Intelligence Research 64 (January 30, 2019): 147–79. http://dx.doi.org/10.1613/jair.1.11337.

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AGM contraction and revision assume an underlying logic that contains propositional logic. Consequently, this assumption excludes many useful logics such as the Horn fragment of propositional logic and most description logics. Our goal in this paper is to generalise AGM contraction and revision to (near-)arbitrary fragments of classical first-order logic. To this end, we first define a very general logic that captures these fragments. In so doing, we make the modest assumptions that a logic contains conjunction and that information is expressed by closed formulas or sentences. The resulting logic is called first-order conjunctive logic or FC logic for short. We then take as the point of departure the AGM approach of constructing contraction functions through epistemic entrenchment, that is the entrenchment-based contraction. We redefine entrenchment-based contraction in ways that apply to any FC logic, which we call FC contraction. We prove a representation theorem showing its compliance with all the AGM contraction postulates except for the controversial recovery postulate. We also give methods for constructing revision functions through epistemic entrenchment which we call FC revision; which also apply to any FC logic. We show that if the underlying FC logic contains tautologies then FC revision complies with all the AGM revision postulates. Finally, in the context of FC logic, we provide three methods for generating revision functions via a variant of the Levi Identity, which we call contraction, withdrawal and cut generated revision, and explore the notion of revision equivalence. We show that withdrawal and cut generated revision coincide with FC revision and so does contraction generated revision under a finiteness condition.
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39

Ryazanova, A. Yu, N. A. Orlova, M. V. Sinegubova, L. K. Dayanova, S. V. Kovnir, S. V. Korobova, V. A. Ledov, A. L. Kovalchuk, P. G. Aparin, and I. I. Vorobiev. "OBTAINING AND ASSESSING IMMUNOGENICITY OF A FUSION PROTEIN WHICH CONSISTS OF A RECEPTOR-BINDING DOMAIN (RBD) OF CORONAVIRUS SARS-COV-2 SPIKE PROTEIN AND A MONOMERIC NON- GLYCOSYLATED FC-FRAGMENT OF HUMAN IGG1." BIOTECHNOLOGY: STATE OF THE ART AND PERSPECTIVES 1, no. 2022-20 (2022): 121–23. http://dx.doi.org/10.37747/2312-640x-2022-20-121-123.

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Variants of genetic constructions are discussed which encode a receptor-binding domain (RBD) of coronavirus SARS-CoV-2 spike protein fused with a monomeric Fc-fragment of human immunoglobulins. A cell line producing RBD-Fc is established. High titers of anti-RBD antibodies and virus-neutralizing antibodies are obtained upon mice immunization with the purified RBD-Fc.
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40

Dighiero, G., S. Hart, A. Lim, L. Borche, R. Levy, and RA Miller. "Autoantibody activity of immunoglobulins isolated from B-cell follicular lymphomas." Blood 78, no. 3 (August 1, 1991): 581–85. http://dx.doi.org/10.1182/blood.v78.3.581.581.

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Abstract Previous work with monoclonal Igs (MIgs) has demonstrated that a high proportion of paraproteins bind to self-antigens such as the Fc fragment of IgG, Ii blood group antigens, cytoskeleton proteins, DNA, and myelin-associated glycoprotein (MAG). Recent work in CLL indicates that CD5+ B lymphocytes are frequently committed to production of autoantibodies. We have examined the antibody specificity of MIgs derived from the tumor cells of 31 different patients with CD5- B-cell lymphomas. Our results indicate that the tumor cells from 8 of these 31 patients (25.8%) express Igs with autoantibody activity. In two cases antibody activity was multispecific. In four cases, antibody activity was exclusively directed against the Fc fragment of IgG, whereas the two other cases bound to both Fc fragment of IgG and nuclear antigens. Most non-Hodgkin's lymphomas (NHL) are derived from CD5- B cells. These results indicate that like CLL, NHL also express Igs that frequently have autoantibody activity.
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41

Dighiero, G., S. Hart, A. Lim, L. Borche, R. Levy, and RA Miller. "Autoantibody activity of immunoglobulins isolated from B-cell follicular lymphomas." Blood 78, no. 3 (August 1, 1991): 581–85. http://dx.doi.org/10.1182/blood.v78.3.581.bloodjournal783581.

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Previous work with monoclonal Igs (MIgs) has demonstrated that a high proportion of paraproteins bind to self-antigens such as the Fc fragment of IgG, Ii blood group antigens, cytoskeleton proteins, DNA, and myelin-associated glycoprotein (MAG). Recent work in CLL indicates that CD5+ B lymphocytes are frequently committed to production of autoantibodies. We have examined the antibody specificity of MIgs derived from the tumor cells of 31 different patients with CD5- B-cell lymphomas. Our results indicate that the tumor cells from 8 of these 31 patients (25.8%) express Igs with autoantibody activity. In two cases antibody activity was multispecific. In four cases, antibody activity was exclusively directed against the Fc fragment of IgG, whereas the two other cases bound to both Fc fragment of IgG and nuclear antigens. Most non-Hodgkin's lymphomas (NHL) are derived from CD5- B cells. These results indicate that like CLL, NHL also express Igs that frequently have autoantibody activity.
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42

Keown, M. B., R. Ghirlando, R. J. Young, A. J. Beavil, R. J. Owens, S. J. Perkins, B. J. Sutton, and H. J. Gould. "Hydrodynamic studies of a complex between the Fc fragment of human IgE and a soluble fragment of the Fc epsilon RI alpha chain." Proceedings of the National Academy of Sciences 92, no. 6 (March 14, 1995): 1841–45. http://dx.doi.org/10.1073/pnas.92.6.1841.

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43

Kenanova, Vania, Tove Olafsen, Desiree M. Crow, Gobalakrishnan Sundaresan, Murugesan Subbarayan, Nora H. Carter, David N. Ikle, et al. "Tailoring the Pharmacokinetics and Positron Emission Tomography Imaging Properties of Anti–Carcinoembryonic Antigen Single-Chain Fv-Fc Antibody Fragments." Cancer Research 65, no. 2 (January 15, 2005): 622–31. http://dx.doi.org/10.1158/0008-5472.622.65.2.

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Abstract Antibody fragments are recognized as promising vehicles for delivery of imaging and therapeutic agents to tumor sites in vivo. The serum persistence of IgG1 and fragments with intact Fc region is controlled by the protective neonatal Fc receptor (FcRn) receptor. To modulate the half-life of engineered antibodies, we have mutated the Fc-FcRn binding site of chimeric anti–carcinoembryonic antigen (CEA) antibodies produced in a single-chain Fv-Fc format. The anti-CEA T84.66 single-chain Fv-Fc format wild-type and five mutants (I253A, H310A, H435Q, H435R, and H310A/H435Q, Kabat numbering system) expressed well in mammalian cell culture. After purification and characterization, effective in vitro antigen binding was shown by competition ELISA. Biodistribution studies in BALB/c mice using 125I- and 131I-labeled fragments revealed blood clearance rates from slowest to fastest as follows: wild-type > H435R > H435Q > I253A > H310A > H310A/H435Q. The terminal half-lives of the mutants ranged from 83.4 to 7.96 hours, whereas that of the wild-type was ∼12 days. Additionally, 124I-labeled wild-type, H435Q, I253A, H310A, and H310A/H435Q variants were evaluated in LS174T xenografted athymic mice by small animal positron emission tomography imaging, revealing localization to the CEA-positive xenografts. The slow clearing wild-type and H435Q constructs required longer to localize to the tumor and clear from the circulation. The I253A and H310A fragments showed intermediate behavior, whereas the H310A/H435Q variant quickly localized to the tumor site, rapidly cleared from the animal circulation and produced clear images. Thus, attenuating the Fc-FcRn interaction provides a way of controlling the antibody fragment serum half-life without compromising expression and tumor targeting.
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44

Michon, J., S. Moutel, J. Barbet, JL Romet-Lemonne, YM Deo, WH Fridman, and JL Teillaud. "In vitro killing of neuroblastoma cells by neutrophils derived from granulocyte colony-stimulating factor-treated cancer patients using an anti-disialoganglioside/anti-Fc gamma RI bispecific antibody." Blood 86, no. 3 (August 1, 1995): 1124–30. http://dx.doi.org/10.1182/blood.v86.3.1124.1124.

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Abstract Neutrophils isolated from cancer patients treated with granulocyte colony-stimulating factor (G-CSF) express high levels of Fc gamma RI. They exhibited an efficient killing of GD2+ neuroblastoma cells in the presence of an antidisialoganglioside (GD2) mouse monoclonal antibody (MoAb; 7A4, IgG3 kappa). However, this cytotoxicity was totally blocked by human monomeric IgG. In contrast, a bispecific antibody (7A4 bis 22/MDX-260), prepared by chemically linking an F(ab') fragment of 7A4 with an F(ab') fragment of an anti-Fc gamma RI MoAb, 22, which binds outside the Fc binding domain, triggered antibody-dependent cell cytotoxicity, even when neutrophils were preincubated with human monomeric IgG. F(ab')2 22 MoAb abrogated the MDX-260 killing without affecting that of 7A4. The 3G8 MoAb, directed against the Fc gamma RIII binding site, did not inhibit the cytotoxicity induced by either antibody. Thus, these results indicate that G-CSF-activated neutrophils exert their cytotoxic effect against neuroblastoma cells through Fc gamma RI and not Fc gamma RIII, and that the saturation of the high affinity Fc gamma RI by monomeric IgG can be overcome by the use of bispecific antibodies binding epitopes outside the IgG Fc gamma RI binding site. A combined administration of such bispecific antibodies and G-CSF may be, therefore, an efficient therapeutic approach to trigger tumor lysis by cytotoxic neutrophils in vivo.
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45

Michon, J., S. Moutel, J. Barbet, JL Romet-Lemonne, YM Deo, WH Fridman, and JL Teillaud. "In vitro killing of neuroblastoma cells by neutrophils derived from granulocyte colony-stimulating factor-treated cancer patients using an anti-disialoganglioside/anti-Fc gamma RI bispecific antibody." Blood 86, no. 3 (August 1, 1995): 1124–30. http://dx.doi.org/10.1182/blood.v86.3.1124.bloodjournal8631124.

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Neutrophils isolated from cancer patients treated with granulocyte colony-stimulating factor (G-CSF) express high levels of Fc gamma RI. They exhibited an efficient killing of GD2+ neuroblastoma cells in the presence of an antidisialoganglioside (GD2) mouse monoclonal antibody (MoAb; 7A4, IgG3 kappa). However, this cytotoxicity was totally blocked by human monomeric IgG. In contrast, a bispecific antibody (7A4 bis 22/MDX-260), prepared by chemically linking an F(ab') fragment of 7A4 with an F(ab') fragment of an anti-Fc gamma RI MoAb, 22, which binds outside the Fc binding domain, triggered antibody-dependent cell cytotoxicity, even when neutrophils were preincubated with human monomeric IgG. F(ab')2 22 MoAb abrogated the MDX-260 killing without affecting that of 7A4. The 3G8 MoAb, directed against the Fc gamma RIII binding site, did not inhibit the cytotoxicity induced by either antibody. Thus, these results indicate that G-CSF-activated neutrophils exert their cytotoxic effect against neuroblastoma cells through Fc gamma RI and not Fc gamma RIII, and that the saturation of the high affinity Fc gamma RI by monomeric IgG can be overcome by the use of bispecific antibodies binding epitopes outside the IgG Fc gamma RI binding site. A combined administration of such bispecific antibodies and G-CSF may be, therefore, an efficient therapeutic approach to trigger tumor lysis by cytotoxic neutrophils in vivo.
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46

Pincetic, Andrew, Alysia Ahmed, Joseph Lomino, Lai-Xi Wang, Pamela Bjorkman, and Jeffrey Ravetch. "The structural basis for the anti-inflammatory activity of sialylated antibodies (THER5P.822)." Journal of Immunology 192, no. 1_Supplement (May 1, 2014): 200.1. http://dx.doi.org/10.4049/jimmunol.192.supp.200.1.

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Abstract Antibodies (Ab) mediate pro-inflammatory effector functions through the engagement of Fc receptors (FcγRs) expressed on leukocytes. A complex, N-linked glycan attached to the Fc domain of IgG regulates the interaction to FcγRs by maintaining the Fc in a biologically active conformation. However, attaching sialic acid sugar residues to this Fc-associated glycan reduces affinity for FcγRs and confers binding to an alternate class of receptors, the C-type lectins (DC-SIGN). This switch in receptor specificity coincides with a switch in effector function in vivo as sialylated IgG (sFc) suppresses inflammation in mouse models of autoimmunity. The structural mechanism that regulates the sialic acid-dependent change in Ab effector function remains poorly understood. Biophysical analysis reveals that sialylation destabilizes the Fc fragment by increasing the hydrophobic surface area exposed to solvent. Upon solving a crystal structure of sFc, we observe that this loss of stability correlates with inter-domain flexibility such that the sFc in the crystal is found in both “open” and “closed” states. Mutagenic analysis of sFc further identifies key contact sites between the Fc-glycan and the Fc-backbone necessary to induce this conformational change and attain anti-inflammatory activity in vivo. These studies demonstrate that the conformational diversity of the Fc fragment serves as a general strategy to shift receptor specificity in order to effect different immunological outcomes.
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47

Huppi, K., B. A. Mock, J. Hilgers, J. Kochan, and J. P. Kinet. "Receptors for Fc epsilon and Fc gamma are linked on mouse chromosome 1." Journal of Immunology 141, no. 8 (October 15, 1988): 2807–10. http://dx.doi.org/10.4049/jimmunol.141.8.2807.

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Abstract Recently isolated cDNA clones for the high affinity Fc epsilon receptors on mast cells and basophils (Fc epsilon RI alpha) and Fc gamma receptors on macrophages and lymphocytes (Fc gamma 2b/gamma 1R) are homologous members of the Ig supergene family. Analysis of the segregation of restriction fragment length polymorphism in crosses of inbred mice now establish that the structural genes encoding both Fc epsilon RI alpha and Fc gamma 2b/gamma 1R are indeed discrete genes and are linked at the distal end of mouse chromosome 1. This finding raises the possibility that a family of Fc receptors could be found in a region that is known to contain immunologically important markers of lymphocyte surface Ag and autoimmune defects.
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48

Gallagher, D. Travis, Chris McCullough, Robert G. Brinson, Joomi Ahn, John P. Marino, and Nazzareno Dimasi. "Structure and Dynamics of a Site-Specific Labeled Fc Fragment with Altered Effector Functions." Pharmaceutics 11, no. 10 (October 21, 2019): 546. http://dx.doi.org/10.3390/pharmaceutics11100546.

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Antibody-drug conjugates (ADCs) are a class of biotherapeutic drugs designed as targeted therapies for the treatment of cancer. Among the challenges in generating an effective ADC is the choice of an effective conjugation site on the IgG. One common method to prepare site-specific ADCs is to engineer solvent-accessible cysteine residues into antibodies. Here, we used X-ray diffraction and hydrogen-deuterium exchange mass spectroscopy to analyze the structure and dynamics of such a construct where a cysteine has been inserted after Ser 239 (Fc-239i) in the antibody heavy chain sequence. The crystal structure of this Fc-C239i variant at 0.23 nm resolution shows that the inserted cysteine structurally replaces Ser 239 and that this causes a domino-like backward shift of the local polypeptide, pushing Pro 238 out into the hinge. Proline is unable to substitute conformationally for the wild-type glycine at this position, providing a structural reason for the previously observed abolition of both FcγR binding and antibody-dependent cellular cytotoxicity. Energy estimates for the both the FcγR interface (7 kcal/mol) and for the differential conformation of proline (20 kcal/mol) are consistent with the observed disruption of FcγR binding, providing a quantifiable case where strain at a single residue appears to disrupt a key biological function. Conversely, the structure of Fc-C239i is relatively unchanged at the intersection of the CH2 and CH3 domains; the site known to be involved in binding of the neonatal Fc receptor (FcRn), and an alignment of the Fc-C239i structure with an Fc structure in a ternary Fc:FcRn:HSA (human serum albumin) complex implies that these favorable contacts would be maintained. Hydrogen deuterium exchange mass spectroscopy (HDX-MS) data further suggest a significant increase in conformational mobility for the Fc-C239i protein relative to Fc that is evident even far from the insertion site but still largely confined to the CH2 domain. Together, the findings provide a detailed structural and dynamic basis for previously observed changes in ADC functional binding to FcγR, which may guide further development of ADC designs.
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49

Endresen, Gerhard K. M. "Interaction between the IgG-Fc fragment and subfragments and the IgG-Fc receptor on human platelets." Thrombosis Research 56, no. 1 (October 1989): 125–30. http://dx.doi.org/10.1016/0049-3848(89)90015-7.

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50

Taylor, Alexander I., Brian J. Sutton, and Rosaleen A. Calvert. "Mutations in an avian IgY-Fc fragment reveal the locations of monocyte Fc receptor binding sites." Developmental & Comparative Immunology 34, no. 2 (February 2010): 97–101. http://dx.doi.org/10.1016/j.dci.2009.08.012.

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