Academic literature on the topic 'Autoantibody reactivity'

Increased antibody reactivity towards self-antigens is often indicative of a disruption of homeostatic immune pathways in the body. In celiac disease, an autoimmune enteropathy triggered by the ingestion of gluten from wheat and related cereals in genetically predisposed individuals, autoantibody reactivity to transglutaminase 2 is reflective of the pathogenic role of the enzyme in driving the associated inflammatory immune response. Autoantibody reactivity to transglutaminase 2 closely corresponds with the gluten intake and clinical presentation in affected patients, serving as a highly useful biomarker in the diagnosis of celiac disease. In addition to gastrointestinal symptoms, celiac disease is associated with a number of extraintestinal manifestations, including those affecting skin, bones, and the nervous system. Investigations of these manifestations in celiac disease have identified a number of associated immune abnormalities, including B cell reactivity towards various autoantigens, such as transglutaminase 3, transglutaminase 6, synapsin I, gangliosides, and collagen. Clinical relevance, pathogenic potential, mechanism of development, and diagnostic and prognostic value of the various identified autoantibody reactivities continue to be subjects of investigation and will be reviewed here.

Abstract Fibrillarin, a component of the U3 RNP particle, is a target for the spontaneously arising autoantibodies in human scleroderma and a monoclonal autoantibody (72B9) derived from the autoimmune mouse strain (NZB x NZW) F1. Autoantibodies against fibrillarin can also be induced in H-2s mice by treatment with mercuric chloride (HgCl2). The objective of this study was to compare the spontaneously occurring anti-fibrillarin autoantibody response with the autoantibody response induced by HgCl2 treatment. Immunofluorescence microscopy on human HEp2, mouse 3T3, and Xenopus XIK-2 cells, immunoblotting with use of nuclear extract from human MOLT-4, mouse 3T3, and Xenopus XIK-2 cells, and immunoprecipitation with use of in vitro translation products of RNA transcripts from yeast fibrillarin cDNA were used in this analysis. Both spontaneous and induced autoantibodies displayed common reactivity in that, irrespective of the antigenic source, they gave the same nucleolar immunofluorescence pattern and a restricted immunoblotting reactivity targeting predominantly the 34-kDa protein fibrillarin. Immunoprecipitation of N- and C-terminal truncated fibrillarin constructs also demonstrated a common pattern of reactivity. All Abs precipitated a fragment comprising amino acids 1-312 but not a smaller fragment containing amino acids 1-257. The majority of sera could not precipitate an N-terminal truncated molecule consisting of amino acids 157-327. These immunoprecipitation experiments support recognition of a common epitope requiring both N- and C-regions, which may be exemplified by the reactivity of murine monoclonal anti-fibrillarin autoantibody 72B9. Our results indicate that spontaneous human and toxin-induced murine autoantibodies to fibrillarin share common reactivity against this highly conserved nucleolar protein.

BackgroundThe autoimmune disease systemic lupus erythematosus (SLE) occurs more frequently in patients of African descent with high morbidity and mortality. Current SLE diagnostic criteria including antinuclear antibody (ANA) reactivity are derived largely from non-African populations. This study characterises ANA reactivity patterns and relates them to SLE clinical presentation in Black African patients.MethodsSera from Black participants (61 patients with SLE and 100 controls) aged 1–81 years were analysed for reactivity against the antigens: uridine 1-ribonuclear protein, Smith uridine-1-5 ribonuclear protein antigen, soluble substance-A, recombinant Ro-52, soluble substance-B, Scl-70, cytoplasmic histidyl-tRNA synthetase antigen, proliferating cell nuclear antigen (PCNA), nucleosomes, ribonuclear P-protein, antimitochondrial antibody M2 (AMA-M2), histones, double-stranded DNA (dsDNA), centromere protein B and polymyositis–sclerosis overlap antigen.FindingsA significantly higher proportion (97%) of the 61 patients with SLE had detectable autoantibody reactivity compared with 15% of the 100 controls (p<0.001). The highest frequencies of autoantibody reactivity in patients with SLE were against the dsDNA antigen (41%) and PCNA (54%). Anti-PCNA and anti-dsDNA reactivity were mutually exclusive (p<0.001) giving rise to two distinct groups of Black African patients with SLE. The first group (n=25) had reactivity profiles consistent with international standard SLE definitions, including anti-dsDNA reactivity, and was 13 times more likely to present with joint symptoms. The larger, second group (n=34), characterised by anti-PCNA and anti-AMA-M2 reactivity, was nine times more likely to present with only cutaneous symptoms.InterpretationOur study demonstrates a need to extend autoantibody panels to include anti-PCNA in the diagnostic process of Black African patients and further refine the predictive values of the reactivity to different antigens to differentiate SLE syndromes in African populations.

Abstract Background International autoantibody standards, traditionally based on material obtained from plasmapheresis of single subjects, represent individual immune response and may not comprehend the heterogeneity of the general population. The anti-DFS70 autoantibody yields a characteristic dense fine speckled (DFS) nuclear pattern on indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA) and speaks against autoimmunity. We propose a novel strategy for developing autoantibody reference standards, based on stepwise pooling of serum samples from hundreds of individuals with anti-DFS70 antibodies. Methods Within a 2-year period, serum samples were selected from routine HEp-2 IFA according to the following criteria: DFS HEp-2 IFA pattern at titer ≥1:640; anti-DFS70 reactivity in three analyte-specific tests (Western blot [WB], enzyme-linked immunosorbent assay [ELISA] and chemiluminescent immunoassay [CLIA]). Aliquots of individual samples were combined into progressively larger pools with stepwise validation of intermediary pools as for individual samples. Validated intermediary pools were merged into a final pool for lyophilization. Results A total of 741 validated samples yielded a 750 mL final pool that was lyophilized into thousands of 200 μL-aliquots. Reconstituted aliquots yielded the expected anti-DFS70 reactivity in ELISA, CLIA and WB, as well as high-titer DFS HEp-2 IFA pattern. The appropriate anti-DFS70 reactivity of the lyophilized pool was confirmed by seven international expert centers, using HEp-2 IFA, ELISA, WB and immunoprecipitation. Conclusions This proof-of-concept study provides an innovative and efficient strategy to build serum reference standards for autoantibody testing. The anti-DFS70 standard will integrate the panel of standards of Autoantibody Standardization Committee (ASC, www.autoab.org), contributing to education for proper assay validation and interpretation of the DFS pattern and other HEp-2 IFA patterns.

Background and objective: Acute disseminated encephalomyelitis (ADEM) and relapsing–remitting multiple sclerosis (RRMS) share overlapping clinical, radiologic and laboratory features at onset. Because autoantibodies may contribute to the pathogenesis of both diseases, we sought to identify autoantibody biomarkers that are capable of distinguishing them. Methods: We used custom antigen arrays to profile anti-myelin-peptide autoantibodies in sera derived from individuals with pediatric ADEM ( n = 15), pediatric multiple sclerosis (Ped MS; n = 11) and adult MS ( n = 15). Using isotype-specific secondary antibodies, we profiled both IgG and IgM reactivities. We used Statistical Analysis of Microarrays software to confirm the differences in autoantibody reactivity profiles between ADEM and MS samples. We used Prediction Analysis of Microarrays software to generate and validate prediction algorithms, based on the autoantibody reactivity profiles. Results: ADEM was characterized by IgG autoantibodies targeting epitopes derived from myelin basic protein, proteolipid protein, myelin-associated oligodendrocyte basic glycoprotein, and alpha-B-crystallin. In contrast, MS was characterized by IgM autoantibodies targeting myelin basic protein, proteolipid protein, myelin-associated oligodendrocyte basic glycoprotein and oligodendrocyte-specific protein. We generated and validated prediction algorithms that distinguish ADEM serum (sensitivity 62–86%; specificity 56–79%) from MS serum (sensitivity 40–87%; specificity 62–86%) on the basis of combined IgG and IgM anti-myelin autoantibody reactivity to a small number of myelin peptides. Conclusions: Combined profiles of serum IgG and IgM autoantibodies identified myelin antigens that may be useful for distinguishing MS from ADEM. Further studies are required to establish clinical utility. Further biological assays are required to delineate the pathogenic potential of these antibodies.

Background: Ovarian cancer (OC) is the most lethal gynaecological cancer. It is often diagnosed at an advanced stage with poor chances for successful treatment. An accurate blood test for the early detection of OC could reduce the mortality of this disease. Methods: Autoantibody reactivity to 20 epitopes of BARD1 and concentration of cancer antigen 125 (CA125) were assessed in 480 serum samples of OC patients and healthy controls. Autoantibody reactivity and CA125 were also tested for 261 plasma samples of OC with or without mutations in BRCA1/2, BARD1, or other predisposing genes, and healthy controls. Lasso statistic regression was applied to measurements to develop an algorithm for discrimination between OC and controls. Findings and interpretation: Measurement of autoantibody binding to a number of BARD1 epitopes combined with CA125 could distinguish OC from healthy controls with high accuracy. This BARD1-CA125 test was more accurate than measurements of BARD1 autoantibody or CA125 alone for all OC stages and menopausal status. A BARD1-CA125-based test is expected to work equally well for average-risk women and high-risk women with hereditary breast and ovarian cancer syndrome (HBOC). Although these results are promising, further data on well-characterised clinical samples shall be used to confirm the potential of the BARD1-CA125 test for ovarian cancer screening.

Abstract SLE is a chronic, recurrent, potentially fatal multisystem inflammatory disorder mainly affecting women. SLE patients produce antibodies to many different self-antigens. Yet, currently used serological markers for SLE are lacking in specificity and/or sensitivity. The aim of this study was to develop an improved diagnostic test by measuring and multiplexing specific autoantibody reactivities in SLE patients. Autoantibody reactivity profiles in serum samples collected from 97 SLE patients within three years of the diagnosis were compared with those of 56 healthy controls. Autoantibody profiles were determined using the ImmunArray iCHIP™ - a proprietary protein microarray technology that allows the display of antigens representing a wide range of SLE-associated biochemical pathways on a single chip. Using this novel platform, SLE patients could be differentiated from healthy subjects by a relatively small subset of auto-antigens and Epstein Barr Virus (EBV) antigens. The autoantibody reactivity profile that allowed SLE diagnosis with high sensitivity and specificity displayed differential response to known SLE-specific antigens, such as single-stranded DNA and EBV, and to several novel ones. Conclusion: An antibody profile for SLE diagnosis using a single multiplexed chip was successfully developed. This profile may differentiate between SLE patients and healthy individuals. Validation of this profile in additional patient samples is ongoing.

Mucous membrane pemphigoid (MMP) is a rare, predominantly mucosal subepithelialblistering disorder triggered by autoantibody reactivity to several basement membrane antigensincluding BP180, BP230, laminin 332, and type VII collagen [...]

La Sclerosi multipla (SM) appartiene ad un folto gruppo di malattie infiammatorie demielinizzanti del sistema nervoso centrale (CNS), in cui la risposta autoimmune è orientata verso la mielina e le cellule produttrici di mielina, gli oligodendrociti, che infine porta a demielinizzazione e perdita oligodendrocitaria. L'eterogeneità nelle alterazioni morfologiche del cervello è rilevabile con risonanza magnetica (MRI), valutazione istopatologica e nella presentazione clinica. Tre sono le principali forme di SM. Non è chiaro quali fattori sono responsabili dei diversi decorsi. La forma Recidivante-remittente (RR)-SM la più frequente (85% -90% dei pazienti), caratterizzata da attacchi imprevedibili (recidive), seguiti da periodi di mesi o anni di relativa tranquillità (sgravio), senza nuovi segni di malattia. La maggior parte dei pazienti con SM-RR può successivamente sviluppare una forma secondaria progressiva (SP)-SM in cui si iniziano ad avere cali neurologici e attacchi acuti senza alcun periodo di remissione. Circa il 10% - 15% dei pazienti si presenta con malattia ad esordio insidioso e costante progressione, questa forma è chiamata primaria progressiva (PP)-MS. E' stato dimostrato che la reazione autoimmune coinvolge sia l'attivazione dei linfociti T che B. L'attivazione di cellule T CD4 + autoreattive e la loro differenziazione in un fenotipo Thl sono eventi cruciali nelle prime fasi, e probabilmente sono importanti anche nel lungo periodo di evoluzione della malattia. I1 danno del tessuto bersaglio, il sistema nervoso centrale, è, tuttavia, molto probabilmente mediato da altre componenti del sistema immunitario, come ad esempio gli anticorpi (IGS), fattori del complemento, cellule T CD8 +, e fattori prodotti cellule dell' immunità innata . L'osservazione che gli IGS presentano valori elevati nel liquido cerebrospinale (CSF) di pazienti con SM è stato di rilevante importanza suggerendo un ruolo delle cellule B e degli anticorpi nella patologia della SM. Nella maggior parte degli studi la ricerca si è concentrata su proteine della mielina e altri complonenti del CNS proteine. Nonostante alcuni studi sottolineano l'importanza di anticorpi specifici della mielina, altri non riescono a confermare questi dati. Abbiamo tentato di superare tali restrittivi approcci utilizzando un ampio pannello di antigeni derivati da estratti del tessuto bersaglio. Nel presente studio, abbiamo confrontato, attraverso elettroforesi bidimensionale su gel di poliacrilamide (2D-PAGE) e immunoblotting, le IgG provenienti dal siero e dal liquido cerebrospinale di pazienti con SM con antigeni di controllo derivati da materia bianca normale del CNS. Gli spot reattivi sono stati quindi individuati tramite spettrometria di massa (MAS) e 1 o immunoblotting. Questo approccio di tipo immunomico ha consentito l'identificazione di un ristretto numero di isoforrne di proteine neuronali riconosciute in maniera specifica dai sieri SM e dai CSF, in gran parte localizzate su oligodendrociti e 1 o citoscheletro. Quasi tutti i pazienti con SM presentano, nel CSF, IgG dirette verso isoforme di proteine da oligodendrociti e10 da citoscheletro. Quasi tutti i pazienti presentano IgG del CSF dirette contro un'isoforma di una delle principali proteine degli oligodendrociti, la molecola Transketolase (TK), contro la proteina cyclic nucleotide phosphodiesterase type I (CNPase I), la collapsin response mediator protein 2 e contro tubulin p4. E' Interessante notare che nei pazienti SM, il 50% delle IgG da CSF riconosce la TK, che è stata in gran parte localizzata su oligodendrociti dalla materia bianca umana normale e da campioni SM. L'autoreattività delle IgG verso proteine del citoscheletro (radixina, sirtuina 2 e proteine che interagiscono con l'actina l) è diffusa maggiormente in pazienti con SM secondaria progressiva. Tra le proteine riconosciute dalle IgG del siero, quasi tutti i pazienti con SM riconoscono in maniera specifica un numero limitato di proteine dei neuronildel citoscheletro, mentre la CNPase è l'antigene più frequentemente riconosciuto (44%) dalle IgG sieriche di pazienti SM. I1 nostro approccio immunomico ha gettato nuova luce sul repertorio autoimmune rivelando nuovi possibili autontigeni oigodendrogliali e10 neuronali, che possono avere potenziali e importanti implicazioni patogeniche e servire inoltre come biomarcatori di malattia in diagnostica.
Multiple Sclerosis (MS) belongs to a large group of inflammatory demyelinating diseases of the central nervous system (CNS), in which the autoimmune response is directed to myelin and myelin-producing cells, the oligodendrocytes, and eventually leads to demyelination and oligodendrocyte loss. Heterogeneity in morphological alterations of the brain is detectable by magnetic resonance imaging (MRI), histopathological evaluation, as well as in clinica1 presentation. Three are the major forms of MS. It is not clear which factors are responsible for the different courses. Relapsing-remitting (M)-MS is the most frequent form (85%-90% of patients) characterized by unpredictable attacks (relapses) followed by periods of months to years of relative quiet (remission) with no new signs of disease activity. Most RR-MS patients later develop secondary progressive (SP)-MS, in which they begin to have neurologic decline between their acute attacks without any definite periods of remission. About 10%-15% of patients present with insidious disease onset and steady progression, termed primary progressive (PP)-MS. The autoimmune reaction has been shown to involve the activation of both T and B lymphocytes. The activation of CD4+ autoreactive T cells and their differentiation into a Thl phenotype are crucial events in the initial steps, and these cells are probably also important players in the long-term evolution of the disease. Damage of the target tissue, the central nervous system, is, however, most likely mediated by other components of the immune system, such as antibodies (Igs), complement, CD8+ T cells, and factors produced by innate immune cells. The observation that Igs are elevated in the cerebrospinal fluid (CSF) of MS patients has been the most important and earliest evidence suggesting a role for B cells and antibodies in the pathology of MS. In most of the studies the search for autoantigens has focused on myelin proteins and other CNS components. Although some studies emphasize the relevance of myelin-specific antibodies, others fail to confirm these data. We have overcome such restrictive approaches using a large pane1 of antigens derived from target tissue extracts. In the present study, we compared by bidimensional polyacrylamide gel electrophoresis (2D-PAGE) and immunoblotting the IgG repertoires from serum and CSF of contro1 and MS patients against antigens derived from CNS normal white matter. The reactive spots were then identified by mass spectrometry (MaS) andlor immunoblotting. This immunomic approach enabled the identification of a restricted number of neural protein isoforms specifically recognized by MS sera and CSF, which were mostly localized on oligodendrocytes andlor cytoskeleton. Almost al1 MS patients had CSF IgG directed to isoforms of one of the oligodendroglial molecules transketolase (TK), cyclic nucleotide phosphodiesterase type I (CNPase I), collapsin response mediator protein 2 and tubulin P4. Interestingly, 50% of MS CSF IgG recognized TK, which was mostly localized on oligodendrocytes in human white matter from normal and MS samples. IgG autoreactivity to cytoskeletal proteins (radixin, sirtuin 2 and actin interacting protein 1) was prevalent in secondary progressive MS patients. Among the proteins recognized by serum IgG, almost al1 MS patients specifically recognized a restricted number of neuronal/cytoskeletal proteins, while CNPase I was the oligodendroglial antigen most frequently recognized (44%) by MS seric IgG. Our immunomic approach shed new light on the autoimmune repertoire present in MS patients revealing nove1 oligodendroglial andlor neuronal putative autoantigens, which may have potential important pathogenic implications and also serve as biomarkers of disease as well as useful diagnostic tools.

Background: The heterogeneity of COVID-19 lies within its diverse symptoms and severity, ranging from mild to lethal. Acute respiratory distress syndrome (ARDS) has been shown to be the leading cause of mortality in COVID-19 patients, characterized by a hyper cytokine storm. Autoimmunity is proposed to occur as a result of COVID-19, given the high similarity of the immune responses observed in COVID-19 and autoimmune diseases. Results: Here, we investigate the level of autoimmune antibodies in COVID-19 patients with different severities. Initial screening for antinuclear antibodies (ANA) IgG revealed that 1.6% (2/126) and 4% (5/126) of ICU COVID-19 cases developed strong and moderate ANA levels, respectively. However, all the non-ICU cases (n = 273) were ANA negative. The high ANA level was confirmed by immunofluorescence (IFA) and large-scale autoantibody screening by phage immunoprecipitation-sequencing (PhIP-Seq). Indeed, the majority of the samples showed "speckled" ANA pattern by microscopy, and we demonstrate that samples of ICU patients with strong and moderate ANA levels contain autoantibody specificities that predominantly targeted proteins involved in intracellular signal transduction, metabolism, apoptotic processes, and cell death; further denoting reactivity to nuclear and cytoplasmic antigens. Conclusion:Our results further support the notion of routine screening for autoimmune responses in COVID-19 patients, which might help improve disease prognosis and patient management. Further, results provide compelling evidence that ANA-positive individuals should be excluded from being donors for convalescent plasma therapy in the context of Covid-19.

Idiopathic thrombocytopenic purpura (ITP) is a syndrome caused by circulating antibodies reactive with the platelet membrane. The antigenic specificity of these antibodies is unknown. We have characterized new monoclonal antibodies that react with a determinant specific to GP Ib and GP Ib- Ia complex, and used flow cytometry to investigate platelets in ITP for antigenic determinants to which autoantibodies are directed. Forty cases of ITP were analyzed in detail by the platelet suspension immunofluorescence test(PSIFT) of von dem Borne et al. The monoclonal antibodies used were 5 against GP Ib-Ia complex (NNKY1-32, NNKY2-5, NNKY2-6, NNKY2-11, NNKY2-18) and 2 against GP lb (NNKY5-4, NNKY5-5). The reactivity of monoclonal antibodies was inhibited by the presence of autoantibody on platelets in some ITP patients. Differences in inhibition were found not only between monoclonal antibodies but also between cases.These results suggest that some ITP patients have circulating antibodies to GP Ib or GP II b - Ia, and that heterogeneous antibodies are present on platelets. Moreover, the presence of these autoantibodies may aggravate or initiate a bleeding tendency.

Platelet membrane glycoproteins (GP) express anumber of antigenic determinants important in theetiology of autoimmune thrombocytopenia. Sensitization to GPIb, although not the most frequent cause of ITP, leads to a particularly severe form ofthe disease. We have identified a number of casesof ITP in which GPIb bears the relevant immunogen. Using GPIb-specific autoantibodies isolated from the plasma of one such patient, we have produced a number of rabbit polyclonal and murine monoclonal anti-idiotypic antibodies. These antibodies recognize an idiotype expressed on the IgM antibody of this patient as well as IgG or IgM antibodies from several other patients with ITP, all of which can be shown to bind specifically to GPIb. Statistical analysis of a series of plasmas from normal individuals and thrombocytopenic patients demonstrated that there is a very strong correlation between the presence of the idiotype and GPIb reactivity, (p < 0.00001). These anti-idiotypic antibodies are useful for the detection and characterization of GPIb-specific antibodies in the sera of patients with a clinically severe form of ITP. The classification of patients bearing this idiotype in their plasma may be useful in predicting disease outcome, thus identifying a group of ITP patients in whom more aggressive therapeutic regimens may be indicated. The use of these reagents and the development of human B lymphoblastoid cell lines producing monoclonal anti-GPIb antibodies will serve to elucidate the clonal origin and cellular regulation of autoantibody production in this disease

In order to clarify human factor VIII inhibitor epitopes to factor VIII (F. VIII), we analyzed the inhibitor IgG developed in the patients with hemophilia A and autoimmune disease using immunoblotting of purified F. VIII and thrombin-degraded F. VIII. IgG fractions were obtained from 6 cases of severe hemophilia A and one autoimmune disease. The titer of the inhibitor plasma ranged from 50 to 3,000 Bethesda units/ml. Purification of F. VIII from commercial F. VIII concentrate was performed by immunoadsorbent column chromatography using anti-von Willebrand factor monoclonal antibody and anti-fibrinogen, anti-fibronectin and anti-IgM goat antibodies and subsequently by Aminohexyl Sepharose column chromatography essentially according to the method of Fulcher et al.. The specific activity of the purified F. VIII was 2,700 units/mg. On sodium-dodecylsulfate (SDS) 5 to 10% gradient polyacrylamide gel electrophoresis (PAGE), 80 kDa of a main fragment and a series of 90 to 210 kDa fragments were visualyzed by Coomassie blue staining. Immunoblotting of 5-10 ug of each of unreduced purified F. VIII and thrombin-degraded F. VIII. followed by reaction with inhibitor IgG samples, monoclonal antihuman IgG-3 and IgG-4 antibodies and radiolabeled rabbit antimouse IgG.All inhibitor IgG samples reacted with both purified F. VIII and thrombin-degraded F. VIII. The pattern of reactivity of inhibitor antibodies was divided into three groups; 1) inhibitor IgG which reacted with 80 and 70 kDa derived from carboxy-terminus of the F. VIII molecule, 2) inhibitor IgG which reacted with 90 to 210 kDa and 54 and/or 44 kDa derived from amino-terminus of the F. VIII, and 3) inhibitor IgG which reacted with both of N- and C-terminus of the F. VIII. One inhibitor IgG belonged to group 3 strongly reacted with a series of higher molecular polypeptides of F. VIII ranged from 180 .to 210 kDa. One autoantibody IgG from the patient with autoimmune disease was also belonged to group 3. There was no relationship between the titer and the pattern of reactivity of each inhibitor plasma. In summary, there is a heterogeneity of F. VIII inhibitor epitopes to F. VIII molecules.