Academic literature on the topic 'Immunodeficienza primitiva'

Immunodeficient individuals are prone to develop a number of opportunistic infections and unique neoplasms. Epstein-Barr virus–associated smooth muscle tumor is an uncommon neoplasm associated with immunodeficiency. It has been described in patients infected with human immunodeficiency virus, in the posttransplant setting, and in those with congenital immunodeficiency. Different anatomic sites can be involved by Epstein-Barr virus–associated smooth muscle tumor, and even multiple locations can contain these unique lesions within the same patient. The presence of variable numbers of intratumoral lymphocytes and primitive round cell areas are the unique defining features for this tumor. Histopathologic features may vary considerably in terms of cellular atypia, mitotic activity, and necrosis, with no correlation to the clinical behavior. Demonstration of Epstein-Barr virus infection by in situ hybridization within tumor cell remains critical for the diagnosis. The mechanism for Epstein-Barr virus infection of progenitor cells and neoplastic transformation has been an area of interest and conjecture. Different treatment strategies are proposed according to underlying disease status. This paper reviews the clinicopathologic features of this uncommon neoplasm with detailed discussion of the role of Epstein-Barr virus in the pathogenesis.

Abstract Mobilized CD34+ cells from human peripheral blood (PB) are increasingly used for hematopoietic stem-cell transplantation. However, the mechanisms involved in the mobilization of human hematopoietic stem and progenitor cells are largely unknown. To study the mobilization of human progenitor cells in an experimental animal model in response to different treatment regimens, we injected intravenously a total of 92 immunodeficient nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with various numbers of granulocyte colony-stimulating factor (G-CSF) –mobilized CD34+ PB cells (ranging from 2 to 50 × 106cells per animal). Engraftment of human cells was detectable for up to 6.5 months after transplantation and, depending on the number of cells injected, reached as high as 96% in the bone marrow (BM), displaying an organ-specific maturation pattern of T- and B-lymphoid and myeloid cells. Among the different mobilization regimens tested, human clonogenic cells could be mobilized from the BM into the PB (P= .019) with a high or low dose of human G-CSF, alone or in combination with human stem-cell factor (SCF), with an average increase of 4.6-fold over control. Therefore, xenotransplantation of human cells in NOD/SCID mice will provide a basis to further study the mechanisms of mobilization and the biology of the mobilized primitive human hematopoietic cell.

Mobilized CD34+ cells from human peripheral blood (PB) are increasingly used for hematopoietic stem-cell transplantation. However, the mechanisms involved in the mobilization of human hematopoietic stem and progenitor cells are largely unknown. To study the mobilization of human progenitor cells in an experimental animal model in response to different treatment regimens, we injected intravenously a total of 92 immunodeficient nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with various numbers of granulocyte colony-stimulating factor (G-CSF) –mobilized CD34+ PB cells (ranging from 2 to 50 × 106cells per animal). Engraftment of human cells was detectable for up to 6.5 months after transplantation and, depending on the number of cells injected, reached as high as 96% in the bone marrow (BM), displaying an organ-specific maturation pattern of T- and B-lymphoid and myeloid cells. Among the different mobilization regimens tested, human clonogenic cells could be mobilized from the BM into the PB (P= .019) with a high or low dose of human G-CSF, alone or in combination with human stem-cell factor (SCF), with an average increase of 4.6-fold over control. Therefore, xenotransplantation of human cells in NOD/SCID mice will provide a basis to further study the mechanisms of mobilization and the biology of the mobilized primitive human hematopoietic cell.

A number of hematologic abnormalities, including cytopenias, have been observed in patients with human immunodeficiency virus (HIV) infection. To elucidate their mechanisms, primitive cells from bone marrow aspirates of 21 patients with HIV-1 infection were quantitated by flow cytometry. The mean percentage of CD34+ cells is not significantly altered in HIV-1-infected patients in comparison with HIV-1- seronegative controls. In contrast, two- and three-color immunofluorescence analysis showed that in all HIV-1 samples, most CD34+ cells coexpressed the CD38 antigen. The proportion of HIV-1- derived CD34+ cells that did not express the CD38 antigen was significantly lower (HIV-1+: mean, 1.73%; controls: mean, 14%; P < .0005) than in controls. Moreover, of Thy-1+ cells, the proportion of CD34+ cells was twofold lower in HIV-1-infected patients (HIV-1+: mean, 12%; controls, 25%, P < .0005), which suggests that phenotypically primitive cells are depleted in HIV-1 infection. In vitro functional analysis in long-term cultures of sorted CD34+ cells from seven HIV-1 patients showed that CD34+ cells from HIV-1 patients generated much fewer colonies both in the nonadherent and adherent layers than CD34+ cells from controls after 5 weeks of culture (10-fold and four-fold less, respectively). Precise long-term culture initiating cell (LTC-IC) frequency in the CD34+ cell population was determined in three patients by limiting dilution and was markedly decreased in comparison to that of normal controls (from twofold to > sevenfold decreased). To determine if primitive cells were infected by HIV-1, both methylcellulose colonies generated from long-term culture of CD34+ cells and various CD34+ cell fractions purified by flow cytometry were evaluated for the presence of HIV-1 by polymerase chain reaction (PCR). Progeny from long-term culture was HIV-1-negative in three samples. In addition, using a sensitive PCR technique, the HIV-1 genome could not be detected in CD34+, CD34+/CD38-, and CD34+/CD4+ cells. These data show that hematologic disorders in HIV disease may be the consequence of a deficit of primitive cells. However, direct infection of these cells by HIV-1 does not seem to be responsible for this defect.

A subset of leukemic cells is assumed to maintain long-term growth of acute myeloid leukemia (AML) in vivo. Characterization of these AML progenitor cells may further define growth properties of human leukemia. In vitro incubations with 5-fluorouracil (5-FU) have been used for enrichment of normal primitive hematopoietic stem cells. By analogy to normal hematopoiesis, it was hypothesized that primitive leukemic stem cells might be kinetically more inactive than colony- forming cells (colony-forming units-AML [CFU-AML]). To examine this hypothesis, conditions were established for incubation with 5-FU that eliminated all CFU-AML. These conditions selected a 5-FU-resistant AML fraction that was evaluated for its capacity for long-term growth by transplantation into mice with severe combined immunodeficiency (SCID) and long-term culture in the quantitative cobblestone area-forming cell (CAFC) assay. Transplantation of the 5-FU-resistant fraction of four cases of AML into SCID mice resulted in growth of AML. Whereas no CFU- AML survived, 31% to 82% of primitive (week-6) CAFC were recovered from the 5-FU-treated cells. Hematopoietic cells proliferating in the CAFC assay were shown to be leukemic by cytologic, cytogenetic, or molecular analysis. The reduction of AML growth as determined by outgrowth of AML in SCID mice was in the same order of magnitude as the primitive (week- 6) CAFC reduction. This indicates that both assays measure closely related cell populations and that the CAFC assay can be used to study long-term growth of AML. These results show a hierarchy of AML cells that includes 5-FU-resistant progenitors. These cells are characterized as primitive (week-6) CAFC and as leukemia-initiating cells in SCID mice.

The Notch ligand, Jagged-1, plays an essential role in tissue formation during embryonic development of primitive organisms. However, little is known regarding the role of Jagged-1 in the regulation of tissue-specific stem cells or its function in humans. Here, we show that uncommitted human hematopoietic cells and cells that comprise the putative blood stem cell microenvironment express Jagged-1 and the Notch receptors. Addition of a soluble form of human Jagged-1 to cultures of purified primitive human blood cells had modest effects in augmenting cytokine-induced proliferation of progenitors. However, intravenous transplantation of cultured cells into immunodeficient mice revealed that human (h)Jagged-1 induces the survival and expansion of human stem cells capable of pluripotent repopulating capacity. Our findings demonstrate that hJagged-1 represents a novel growth factor of human stem cells, thereby providing an opportunity for the clinical utility of Notch ligands in the expansion of primitive cells capable of hematopoietic reconstitution.

Abstract Stromal-derived factor 1 (SDF-1) is a -CXC- chemokine that plays a critical role in embryonic and adult hematopoiesis, and its specific receptor, CXCR4, has been implicated in stem cell homing. In this study, it is shown that the addition of SDF-1 to long-term cultures (LTCs) of normal human marrow can selectively, reversibly, and specifically block the S-phase entry of primitive quiescent erythroid and granulopoietic colony-forming cells (CFCs) present in the adherent layer. Conversely, addition of anti–SDF-1 antibody or SDF-1(G2), a specific CXCR4 antagonist, to preactivated human LTCs prevented both types of primitive CFCs from re-entering a quiescent state, demonstrating that endogenous SDF-1 contributes to the control of primitive CFC proliferation in the LTC system. Interestingly, SDF-1 failed to arrest the proliferation of primitive chronic myeloid leukemia CFCs in the adherent layer of LTCs containing normal marrow stromal cells. In vivo, injection of SDF-1 arrested the cycling of normal human LTC-initiating cells as well as primitive CFCs in the marrow of nonobese diabetic/severe combined immunodeficient mice engrafted with human cord blood cells. Conversely, injection of the antagonist, SDF-1(G2), reactivated the cycling of quiescent primitive human CFCs present in the marrow of mice engrafted with human marrow cells. These studies are the first to demonstrate a potential physiological role of SDF-1 in regulating the cell-cycle status of primitive hematopoietic cells and suggest that the deregulated cycling activity of primitive chronic myeloid leukemia (CML) cells is due to the BCR-ABL–mediated disruption of a pathway shared by multiple chemokine receptors.

Abstract Efforts to change the fate of human hematopoietic stem cells (HSCs) and progenitor cells (HPCs) in vitro have met with limited success. We hypothesized that previously utilized in vitro conditions might result in silencing of genes required for the maintenance of primitive HSCs/HPCs. DNA methylation and histone deacetylation are components of an epigenetic program that regulates gene expression. Using pharmacologic agents in vitro that might possibly interfere with DNA methylation and histone deacetylation, we attempted to maintain and expand cells with phenotypic and functional characteristics of primitive HSCs/HPCs. Human marrow CD34+ cells were exposed to a cytokine cocktail favoring differentiation in combination with 5aza 2′deoxycytidine (5azaD) and trichostatin A (TSA), resulting in a significant expansion of a subset of CD34+ cells that possessed phenotypic properties as well as the proliferative potential characteristic of primitive HSCs/HPCs. In addition, 5azaD- and TSA-pretreated cells but not the CD34+ cells exposed to cytokines alone retained the ability to repopulate immunodeficient mice. Our findings demonstrate that 5azaD and TSA can be used to alter the fate of primitive HSCs/HPCs during in vitro culture.

Abstract The transplantation of primitive human cells into sublethally irradiated immune-deficient mice is the well-established in vivo system for the investigation of human hematopoietic stem cell function. Although mast cells are the progeny of hematopoietic stem cells, human mast cell development in mice that underwent human hematopoietic stem cell transplantation has not been reported. Here we report on human mast cell development after xenotransplantation of human hematopoietic stem cells into nonobese diabetic severe combined immunodeficient \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((\mathrm{NOD{/}SCID}){/}{\gamma}_{\mathrm{c}}^{null}\) \end{document} (NOG) mice with severe combined immunodeficiency and interleukin 2 (IL-2) receptor γ-chain allelic mutation. Supported by the murine environment, human mast cell clusters developed in mouse dermis, but they required more time than other forms of human cell reconstitution. In lung and gastric tract, mucosal-type mast cells containing tryptase but lacking chymase located on gastric mucosa and in alveoli, whereas connective tissue-type mast cells containing both tryptase and chymase located on gastric submucosa and around major airways, as in the human body. Mast cell development was also observed in lymph nodes, spleen, and peritoneal cavity but not in the peripheral blood. Xenotransplantation of human hematopoietic stem cells into NOG mice can be expected to result in a highly effective model for the investigation of human mast cell development and function in vivo.

La sindrome di DiGeorge (DGS) è causata da una delezione in emizigosi del locus 22q11.2 responsabile di difetti embriogenetici che determinano l’alterazione del timo e delle ghiandole paratiroidee, difetti cardiaci e anomalie facciali caratteristiche. In molti pazienti affetti da questa sindrome, il difetto immunitario è principalmente del compartimento T, sebbene siano state riportate anche anomalie quali disgammaglobulinemia, deficit di IgA e di cellule B della memoria. Sulla base dei dati immunologici, i pazienti DGS sono classificati in DGS completi (cDGS) e DGS parziali (pDGS): i cDGS corrispondono ad una rara forma di immunodeficienza grave combinata (0,5-1%), mentre i pDGS presentano una forma variabile di linfopenia T (da leggera a moderata). Dal punto di vista clinico, questi pazienti mostrano un ampio spettro d’infezioni insieme ad una disregolazione del sistema immunitario con manifestazioni atopiche e autoimmunitarie. I livelli cellulari T, sebbene ridotti, non sono predittivi del rischio di infezioni o autoimmunità. Le alterazioni della distribuzione del repertorio del recettore delle cellule T (TCR) e il ridotto apporto timico nei pazienti pDGS è stato variabilmente associato ad un maggior rischio di infezioni o autoimmunità. Per meglio definire alcuni aspetti della patogenesi e delle caratteristiche immunologiche, abbiamo studiato la cinetica della ricostituzione immunologica in una coorte di pazienti pDGS e in pazienti affetti da altre immunodeficienze primitive non direttamente riconducibili ad alterazioni del compartimento di cellule T (come pazienti con Malattia Granulomatosa Cronica - CGD). A tal fine sono state analizzate le cellule mononucleate del sangue periferico valutando: 1. Il fenotipo e le funzioni immunologiche tramite tecniche convenzionali. 2. La distribuzione del repertorio del TCR dei compartimenti cellulari T CD4+ e T CD8+ (TCRBV spectratyping). 3. L’immunofenotipo di maturazione delle cellule B. 4. La frequenza delle cellule nTreg. La correlazione tra il profilo immunologico in vitro e le caratteristiche cliniche può aiutare a chiarire alcuni aspetti della patogenesi e del difetto immunologico, al fine di identificare dei possibili indicatori di suscettibilità verso le infezioni o verso lo sviluppo di autoimmunità. Risultati e Discussione: I pazienti pDGS mostravano un ridotto numero di cellule T, sebbene non sia stata trovata una correlazione tra i bassi valori di cellule T e le infezioni ricorrenti. Il numero totale di cellule B nei pazienti pDGS e CGD era normale, sebbene sia stato osservato un significativo decremento di cellule B della memoria. La frequenza delle cellule T regolatorie naturali dei pazienti non mostrava differenze se confrontata con i valori dei controlli sani di pari età. La risposta linfoproliferativa verso ogni stimolo era statisticamente diminuita in tutti i pazienti. La distribuzione delle famiglie dei TCRBV è risultata perturbata, con maggiore rilevanza nelle cellule T CD8+ sia nei pazienti pDGS che in quelli CGD. In particolare, l’alterazione delle famiglie TCRBV ha mostrato una tendenza di normalizzazione nella distribuzione del repertorio delle cellule T (sia CD4+ che CD8+), come osservato anche in pazienti infetti da CMV. Le infezioni ricorrenti correlavano con una maggiore frequenza di alterazioni delle famiglie TCRBV nei pazienti pDGS ma non nei pazienti CGD. Sebbene nella sindrome DiGeorge i bassi valori di cellule T non siano predittivi delle infezioni, le maggiori alterazioni delle famiglie TCRBV, così come l’immunodeficienza umorale e la ridotta frequenza di cellule B della memoria CD27+, risultavano essere associati a un maggiore rischio di infezioni in questi pazienti. L’analisi dei pazienti CGD ha mostrato delle alterazioni significative sia nel compartimento cellulare T che in quello B, suggerendo che le alterazioni quantitative e qualitative trovate, possono contribuire alla eterogeneità del fenotipo clinico. Ulteriori studi sono necessari per delucidare come il sistema della NADPH ossidasi è coinvolto nell’alterazione immunologica dei pazienti CGD. In conclusione, le nostre analisi nelle PID hanno rilevato che altri compartimenti cellulari, oltre a quelli noti, possono essere coinvolti in queste malattie. Pertanto alcuni parametri come la distribuzione delle famiglie del TCRBV e la valutazione della maturazione delle cellule B dovrebbero essere usati come indicatori prognostici del rischio d’infezioni nel corso del follow-up per intraprendere eventuali terapie specifiche.
DiGeorge syndrome (DGS) is caused by a deletion in hemizygosis of 22q11.2 locus responsible for embryogenesis defects causing alterations of thymus and parathyroid glands, cardiac defects and abnormal facial features. In most patients, the immune defect is basically in T cell subset although abnormalities such as dysgammaglobulinemia, IgA and memory B cells deficiency have been also reported. On the basis of the immunologic findings, DGS patients are divided in complete DGS (cDGS), a rare form of severe combined immune deficiency (0.5-1%), and partial DGS (pDGS) presenting mild/moderate T cell lymphopenia. Clinically, these patients display a wide spectrum of infections together with a dysregulation of immune system as atopic and autoimmune manifestations. T cell levels, although reduced, are not predictive of the risk to develop infections or autoimmunity. The alterations of the T cell receptor (TCR) repertoire distribution and impaired thymic output in pDGS have been variably associated to a higher risk of infections or autoimmunity. In order to better define some aspects of the pathogenesis and immunological features we studied the kinetic of immune reconstitution in a cohort of pDGS patients and in patients affected by other primary immunodeficiencies not directly affecting T-cell compartments (as Chronic Granulomatous Disease patients) through peripheral blood mononuclear cells (PBMC) analysis of: 1. Phenotype and immunologic functions through standard techniques. 2. TCR repertoire distribution of T CD4+ and T CD8+ subsets (TCRVB spectratyping). 3. Immunophenotypic B-cell maturation. 4. Frequency of T regulatory cells. The correlation between the in vitro immunological profile and the clinical features might help to clarify some aspects of the pathogenesis of the immunological defects, in order to identify possible prognostic markers of increased risk of susceptibility to infections or of development of autoimmunity. Results and Discussion: pDGS patients exhibited decreased T-cell numbers, although no correlation was found between low T-cell values and recurrent infections. Total B-cell numbers in pDGS and CGD patients were normal, although a significantly decreased proportion of memory B cells was observed. No difference in natural T regulatory cells frequency was evident when compared with healthy controls in any groups. A statistical reduced lymphoproliferative response to stimuli (PHA, OKT3 and PWM) in all patients was observed. TCRBV family distribution resulted perturbed, with higher degree in CD8+ T-cell subset in both CGD and pDGS patients. Particularly, TCRBV family alterations in pDGS patients showed a trend of normalization in T cell repertoire distribution (both CD4+ and CD8+ T-cell), as observed in CMV congenital infected patients. Recurrent infections correlated with a high frequency of TCRBV family alterations in pDGS but not in CGD patients. Although low T-cell values were not predictive of recurrent infections in DiGeorge syndrome, higher TCRBV family alterations, as well as humoral immunodeficiency and reduced CD27+ B cell memory frequency, were associated to an increased risk of infections in these patients. Interestingly analysis of CGD patients showed significative alterations in both T and B cells compartments, suggesting that quantitative and qualitative alterations found, might contribute to the heterogeneity in the clinical phenotype. Further studies are needed to elucidate how NADPH oxidase system is involved in CGD patients immune alterations. In conclusion, our analysis on PID patients with well known defective cell compartments revealed that other subsets were also involved, therefore some parameters such as TCRBV family distribution and B-cell maturation could be used as further prognostic markers for follow-up and specific treatment.

2011/2012
La sindrome di Hermansky-Pudlak definisce un gruppo di immunodeficienze primarie rare caratterizzate da albinismo parziale, di tipo autosomico recessivo che si presentano con un quadro di infezioni ricorrenti e predisposizione ad emorragie. I geni causativi di queste patologie codificano proteine coinvolte nella biogenesi e nel trasporto di organelli intracellulari correlati a endosomi e lisosomi. Il caso giunto alla nostra attenzione presentava solo alcuni dei sintomi caratteristici di queste immunodeficienze. Escluse le malattie genetiche più note tramite sequenziamento diretto si è ricorso ad exome sequencing in modo da poter rilevare anche nuove variazioni non note. E' stata infatti riscontrata una mutazione in omozigosi sul gene PLDN (BLOC1S6), codificante una proteina chiamata Pallidina, una componente del complesso BLOC-1. La condizione risultante è stata identificata con il nome di “sindrome di Hermansky-Pudlak di tipo 9” (HPS-9). In questo studio dimostriamo che tale mutazione è associata alla patologia e che compromette la funzionalità del reparto immunitario sia citotossico (linfociti Natual Killer e CD8+) sia presentante l'antigene (cellule dendritiche).
XXV Ciclo

Chaque individu est exposé quotidiennement à des agents infectieux comme les bactéries, les champignons, les virus et les parasites sans pour autant développer une maladie. Cependant, certains vont développer des infections graves et récurrentes, causées par des microbes dont certains ont un faible pouvoir pathogène pour l’homme. Ceci suggère, qu’il existe entre les individus sensibles et résistants une variabilité au niveau du système immunitaire. Deux types de déficits immunitaires primitifs (DIP) de transmission mendélienne ont été décrits. Les DIP dit « classiques » sont monogéniques et prédisposent majoritairement à une susceptibilité infectieuse à large spectre d’agents pathogènes (un gène, plusieurs infections). Les seconds DIP sont également monogéniques mais sont responsables d’une susceptibilité infectieuse réduite à un groupe de pathogènes (un gène, un seul type d’infection). Chez de nombreux, patients, le défaut génétique responsable de DIP n’est pas identifié. Dans ce contexte, l’objectif de recherche de mon doctorat a été de caractériser deux DIP responsables d’une susceptibilité aux infections bactériennes. J’ai tout d’abord mis en évidence un nouveau mécanisme physiopathologique de la protéine NEMO, régulateur de la voie NF-κB, responsable d’un DIP associé à une dysplasie ectodermale anhidrotique (EDA). Ce mécanisme pathologique est caractérisé par une expression et une structure protéique conservées mais confère sélectivement un défaut de liaison de NEMO à l’ubiquitine, interaction essentielle dans l’activation de la voie NF-κB. Ceci démontre qu’une expression et une structure protéique normales n'excluent en rien un rôle pathologique de mutations dans le gène NEMO, dans un EDA-DIP. Dans un deuxième temps, j’ai mis en évidence un nouveau DIP affectant la voie de l’explosion oxydative spécifiquement dans les polymorphonucléaires et qui confère une susceptibilité sélective aux infections bactériennes de type pyogènes. Le patient étudié est né de parents consanguins et a présenté des infections récurrentes des voies respiratoires supérieures ainsi qu’une cellulite à Staphylococcus epidermidis. Par une approche génétique associant analyse de liaison et séquençage de l'exome, une mutation homozygote rare a été identifiée dans le gène codant NRAMP1. Cette mutation co-ségrège avec la maladie selon un mode de transmission autosomique récessif et altère spécifiquement l’expression de la protéine dans les granulocytes. Ce premier déficit en NRAMP1 décrit chez l’homme, compromet à la fois la voie de l’explosion oxydative et le contrôle de l’infection in vitro par Staphylococcus aureus dans les granulocytes. Cette étude implique NRAMP1 dans l'immunité contre les bactéries pyogènes via son rôle dans la production des espèces réactives de l’oxygène dans les granulocytes. Ce travail ouvre la voie vers un meilleur diagnostique et conseil génétique pour les patients souffrant de PID
Human populations are exposed to infectious agents such as bacteria, fungi, viruses and parasites on a daily basis without developing any disease. However, a minority of individuals will suffer from infections to some microbes that are usually non-pathogenic to man, or will undergo severe and/or recurrent diseases usually easily treatable for others. This means that there is variability among individuals regarding their immune system, underlined by genetics between susceptible and resistant individuals. Two types of primary immuno deficiencies with a Mendelian mode of inheritance have been described. The first known as the classical primary immunodeficiency and is monogenic and predisposes in general to infections with a broad spectrum of infectious agents (one gene, multiple infections). The second type is also monogenic but predisposes generally to infections limited to a particular group of pathogens (one gene, one type of infection). The aim of my doctoral research was to characterize two new immunodeficiencies. First I highlighted a new physiopathological mechanism of the NEMO protein, a regulator of NF-κB pathway. This defect is characterized by normal protein expression and folding, but a specific defect of NEMO’s ubiquitin binding, which is an essential mechanism for the activation and regulation of the NF-κB pathway. This demonstrates that normal expression and structure of the protein do not exclude a pathological role of NEMO mutations in EDA-ID. I also described a new immune deficiency affecting the respiratory burst pathway in granulocytes which specifically confers a selective susceptibility to pyogenic bacterial infections. We studied a patient who was born from consanguineous parents, and who suffered from recurrent infections of the upper respiratory tract and cellulitis to S. epidermidis. By a genetic approach involving linkage analysis and exome sequencing, I identified a rare homozygous mutation (V484M) in the gene encoding for the NRAMP1 protein that co segregates with the disease with an autosomal recessive transmission. Specifically, this mutation impairs NRAMP1 protein expression in granulocytes, while expression remains normal in other phagocytic cells. NRAMP1 deficiency impairs both the respiratory burst and control of in vitro infection by S. aureus in granulocytes. Therefore, we identified the first NRAMP1 human deficiency. The mutation selectively affects granulocytes and is clinically responsible for pyogenic infections. This study helps to delineate the role of NRAMP1 in immunity against pyogenic bacteria through its involvement in reactive oxygen species production in granulocytes

Les cellules lymphoïdes innées (ILCs) sont des populations cellulaires d’identification récente, mais leur rôle in vivo chez l’homme reste mal connu. Dans une 1ère étude, nous avons pu montrer qu’un déficit sévère en NK au cours de déficits immunitaires communs variables est associé à un risque accru de manifestations non infectieuses et infectieuses bactériennes sévères, suggérant un rôle protecteur non redondant des cellules NK lorsque le système immunitaire adaptatif n’est pas fonctionnel. Dans une 2ème étude, nous avons montré que des patients atteints de déficits immunitaires combinés sévères ɣc et JAK3 déficients n’ont pas d’ILCs. Après allogreffe de moelle osseuse, le nombre d’ILCs circulantes reste indétectable, sans manifestation clinique notable associée. Ces résultats sont en faveur d’une redondance des fonctions des ILCs chez l’homme, lorsque les fonctions T et B sont conservées. Nous avons ensuite étudié les modifications phénotypiques et fonctionnelles des cellules NK au cours du purpura thrombopénique immunologique, et observé un défaut de production d’interféron-ɣ par les cellules NK circulantes et une augmentation de la cytotoxicité dépendante des anticorps des cellules NK spléniques. Une inhibition des fonctions des cellules NK par les immunoglobulines polyvalentes est également mise en évidence. Enfin, une étude des ILCs circulantes au cours de la maladie associée aux IgG4 ainsi qu’une revue de la littérature sur l’étude des ILCs au cours des pathologies inflammatoires sont rapportées. En conclusion, l’apparente redondance des ILCs chez l’homme ainsi que leur implication en pathologies inflammatoires en font de potentielles cibles thérapeutiques
Innate lymphoid cells (ILCs) are recently identified components of the immune system, but their functions in vivo in humans are still elusive. In a first study, we show in patients with common variable immunodeficiency that non-infectious inflammatory complications and severe bacterial infections were more frequent in patients with severe NK cell lymphopenia, indicating potential non-redundant immune functions of NK cells when the adaptive immune response is not optimal. In a second study, we observe that in patients with ɣc and JAK3 severe combined immunodeficiencies, all ILC subsets are absent. After hematopoietic stem cell transplantation, ILCs remain indetectable with no susceptibility to disease, suggesting that ILCs might be redundant and dispensable in humans, if T and B cells functions are preserved. In the second part of this thesis, we study phenotypic and functional modifications of NK cell compartment in primary immune thrombocytopenia. Interferon gamma production by the peripheral blood NK cells of ITP patients is decreased. In contrast, splenic NK cells of ITP patients tend to be more efficient in antibody-dependent cell cytotoxicity. Intravenous polyvalent immunoglobulins lead to the inhibition of blood NK cell activation. Finally, we present the preliminary results of a study investigating the modifications of circulating ILCs in IgG4-related disease, and present an extensive litterature review concerning the role of ILCs in inflammatory diseases. In conclusion, the apparent redundancy of ILCs for protective immunity and their pathogenic role in inflammatory diseases make their targeting in humans for therapeutic purposes particularly promising

Viene analizzata l'epidemiologia delle immunodeficienze in Slovenia e Friuli venezia Giulia. Vengono valutati i sintomi di presentazione di immunodeficienza in base all'età di esordio e di diagnosi e gli esami di laboratorio più utili nell'iter diagnostico.
L'identificazione di nuovi tipi di immunodeficienza richiede una rivalutazione delle strategie di sospetto e diagnosi. Sulla base delle nuove conoscenze e di un'analisi della casistica osservata presso l'Istituto Burlo Garofolo e presso la Clinica Pediatrica di Lubiana, vengono formulati alcuni consigli per migliorare il sospetto e la diagnosi delle diverse immunodeficienze.
IRCCS Burlo Garofolo, progetto RC 03/09