The haematopoietic phosphatase PTPN22 is a key regulator in balancing immune responses between self-reactivity and tolerance. PTPN22 downregulates T cell signaling and harbors the non-HLA genetic variation most strongly associated with autoimmune disease in humans, the single nucleotide polymorphism R620W. The effect of this mutation is currently controversial due to confounding results in mouse and human models. The polymorphism is linked to increased susceptibility to autoimmunity in both human and mouse models, although the latter does depend on genetic background. However, mouse data clearly shows that the polymorphism has a loss-of-function effect on T cell signalling, whereas studies in human models largely demonstrate a gain-of-function effect for R620W. A confounding issue in human studies is that they depend on comparison of T cells from distinct individuals, on protein over-expression, or on RNA interference, techniques for which it is difficult to control for genetic and environmental variables, changes in stoichiometry, and off-target effects or incomplete knockdown, respectively. We aimed to create isogenic human cell lines with mutations in PTPN22 at the genomic level to alleviate the complications inherent in analysing human data. In addition to autoimmune pathogenesis, we are interested in the role of PTPN22 in a cancer setting. Because PTPN22 has a strong suppressive effect on T cell responses to weak affinity antigen, which encompass most tumour antigens, we postulated that knocking out PTPN22 may better enable T cells to kill tumour cells. Furthermore, we have shown that PTPN22 knockout (KO) leads to increased IL-2 expression in mouse T cells, and that this effect is protective against TGF-β mediated suppression, a common driver of T cell inhibition in the tumour microenvironment. T cell transfer experiments in mice showed that PTPN22 KO T cells are indeed more effective at reducing tumour size. Based on these findings, we aim to determine whether PTPN22 KO in human cells confers a similar effect on signaling. To investigate the effects of PTPN22 KO on human T cell signaling, we used CRISPR gene-editing to target PTPN22 in a Jurkat cell line. By combining this technique with lentiviral transduction of a specific T cell receptor, we generated human cell lines which are genetically identical, save for specific alterations to PTPN22, and which can be stimulated with strong or weak cognate antigen. We found that PTPN22 KO Jurkat cells develop an enhanced activation phenotype upon stimulation, including increased IL-2 expression. Additionally, PTPN22 KO Jurkat cells show enhanced Erk signalling following stimulation with weak affinity antigen, but this difference is lost as stimulus strength increases. CRISPR technology has presented the opportunity to create novel models of PTPN22 signalling in the context of human T cell lines. The data from these lines suggests that, unlike the R620W mutation, complete loss of PTPN22 has a comparable effect in human and mouse T cells. In conjunction with our previous findings, these results suggest that knocking out PTPN22 may lead to signalling alterations that improve adoptive T cell cancer therapy.

Introdução: Os pênfigos vulgar (PV) e foliáceo (PF) são dermatoses autoimunes vésico-bolhosas que apresentam anticorpos da classe IgG dirigidos contra desmogleínas 1 (Dsg) 1 e 3, cuja consequência é a clivagem intraepitelial (acantólise). Objetivo: Caracterizar o perfil clínico e imunológico dos doentes de PF ou PV com envolvimento umbilical. Métodos: Dez pacientes de pênfigo (vulgar ou foliáceo) com manifestação umbilical, acompanhados no Hospital das Clínicas, Departamento de Dermatologia da Faculdade de Medicina da Universidade de São Paulo foram analisados no período entre agosto de 2008 e janeiro de 2010, segundo suas características clínicas, histopatológicas e imunológicas (imunofluorescência direta, indireta e ELISA utilizando Dsg1 e Dsg3 recombinantes). Resultados: Os dados demográficos identificaram que, dos 10 pacientes incluídos, sete eram mulheres, e três homens; a idade variou entre 2470 anos, e a duração da enfermidade entre três e 16 anos. Cinco pacientes foram diagnosticados como PV e cinco como PF. Eritema, erosões, crostas e lesões vegetantes foram as características clínicas mais relevantes presentes nas regiões umbilicais. A imunofluorescência direta (IFD) da região umbilical mostrou depósitos de IgG e C3 intercelulares intraepiteliais em oito doentes, e IgG isolada em dois indivíduos. A imunofluorescência indireta (IFI) com conjugado IgG mostrou padrão típico intercelular de pênfigo em todos os 10 pacientes, com títulos variando entre 1 : 160 e 1:2560. ELISA Dsg1 recombinante mostrou índices de 24 a 266 no PF, e de 0 a 270 no PV. A reatividade contra Dsg3 recombinante foi positiva em todos os pacientes com PV (ELISA 2298), e mostrou-se negativa em todos os soros de PF. Conclusões: Todos os 10 pacientes com pênfigo com manifestação umbilical demonstraram perfil clínico e imunológico compatíveis com PF ou PV. Esta apresentação peculiar, ainda não bem elucidada, é raramente descrita na literatura. Uma possível explicação para esta apresentação distinta pode ser atribuída à presença de novos epítopos, ou uma associação com vestígios embrionários ou de cicatrizaçào, localizados na região do cordão umbilical / Background: Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune vesicobullous disorders with IgG autoantibodies directed against desmoglein (Dsg)1 and 3, which lead to intraepidermal acantholysis. Aim: To characterize the clinical and immunological profile of patients with PF or PV with umbilical involvement. Methods: Ten patients from the Outpatient Clinic, Hospital das Clínicas, Departamento de Dermatologia da Faculdade de Medicina da Universidade de São Paulo, diagnosed with either PV (n = 5) or mucocutaneous PF (n = 5) with umbilical lesions were assessed according to their clinical features, histopathology and immunological findings [direct and indirect immunofluorescence (DIF and IIF) and ELISA with recombinant Dsg1 and Dsg3]. Patients were evaluated from August 2008 to January 2010. Results: Demographic data showed that from 10 patients, seven were women, and three men; age ranged from24 to70 years-old, disease duration was from 3 to 16 years). Erythema, erosions, crusts and vegetating skin lesions were the main clinical features of the umbilical region. DIF of the umbilical lesion gave positive results for intercellular epidermal IgG and C3 deposits in eight patients and for IgG alone in the other two. Indirect immunofluorescence with IgG conjugate showing the typical pemphigus pattern was positive in all 10 patients, with titres varying from 1: 160 to 1:2560. ELISA with recombinant Dsg1 gave scores of 24266 in PF and 0 270 in PV. Reactivity to recombinant Dsg3 was positive in all five patients with PV (ELISA 2298) and was negative in all PF sera. Conclusions: All 10 patients diagnosed as pemphigus with umbilical presentation had the clinical and immunopathological features of either PF or PV. This peculiar presentation, not yet completely elucidated, has been rarely reported in the literature. A possible explanation for this unique presentation may be the presence of either novel epitopes or an association with embryonic or scar tissue located in the umbilical-cord region

Background: Juvenile idiopathic arthritis (JIA) refers to a group of auto-immune conditions involving joint inflammation that first appears before the age of 16. In the United States, about 294,000 children are affected. Although JIA can be widely attributed to genetic factors, the consensus is that environmental factors also play a role. Attempts to assess the role of environmental factors, though scarce, have focused on the role of infections, smoking exposure, and breastfeeding. Hygiene hypothesis, which suggests that adaptive immunological response improves with higher frequencies of pathogen exposure in early childhood, has been used to try to explain the risk of JIA. Common markers of microbe exposure in early life include sibling number, pet number, and maternal parity. Some prior studies conducted outside the U.S. suggests that increasing sibling number is protective against the risk of JIA. This study aimed to evaluate prior findings, using data from the U.S. Methods: The study used data from the 2017 Centers for Disease Control and Prevention National Survey for Child Health. The survey used a sample size of 21599 children to estimate the number of children in the U.S. Descriptive statistics was carried out, and logistic regression was used to determine the association between family number and the odds of developing JIA, while adjusting for sociodemographic variables. Family number was used as a proxy for sibling number. SAS v 9.4 was used for analysis. Results: Complete data on all the variables of interest were available for 17618 children, of which 67 had JIA. Although there was a marginal association between sibling number and JIA in the unadjusted model (OR [95% CI] 0.983-1.602) (P=0.068), in the adjusted model, there was no significant association between JIA and sibling number ([OR 95% CI] 0.8985-1.447) (P=0.29). There was a significant association between JIA and age, low birth weight, highest education level in the family, while sex had a marginal association. Conclusion: There was no association between family size and the development of JIA in this study. While some prior results have supported the observed significant effect of low birth weight, the disparity in results between this study and the Australian study could be due to the use of family number instead of sibling number. Further studies should assess the association of sibling number and developing JIA in the U.S.

Les Lymphocytes T CD4 (LT CD4) sont des cellules du système immunitaire adaptatif extrêmement plastiques qui, en fonction des signaux présents dans le microenvironnement cellulaire, ont la capacité de se différencier en différentes sous-populations de LT CD4 possédant des fonctions distinctes. Ce processus est hautement régulé par l'expression de facteurs de transcription (FT) clés tels que T-Bet, GATA-3, RORgammaT et Foxp3, nécessaires à la mise en place des lignages Th1, Th2, Th17 et Treg respectivement. Néanmoins, ces protéines n'agissent pas seules, et d'autres facteurs de transcription sont nécessaires pour amplifier, soutenir et maintenir ces différents lignages. Chaque lignage permet de lutter efficacement face à différents types de pathogènes ; toutefois, si la réponse immune n'est pas adaptée, ils peuvent également être responsables du développement de maladies auto-immunes. Afin de mettre en évidence les voies de signalisation et les facteurs de transcription impliqués dans la différenciation des LT CD4 pathogènes, nous avons utilisé le modèle de l'Encéphalomyélite Auto-immune Expérimentale (EAE), un modèle murin de Sclérose En Plaques (SEP). Dans ce modèle, nous avons mis en évidence le rôle clef de deux facteurs de transcription, Foxo3 et Eomes, dans la différenciation des LT CD4. En effet, les souris déficientes en Foxo3 développent une EAE moins sévère que les souris WT, et cette moindre sévérité de la maladie est associée à une proportion réduite de cellules productrices d'IFN-gamma et de GM-CSF in vivo, suite à l'immunisation. L'analyse du transcriptôme des souris Foxo3KO et WT a révélé que la déficience en Foxo3 a pour conséquence une diminution drastique de l'expression du FT Eomes. Bien que cette protéine soit nécessaire à la mise en place des réponses cytotoxiques dans les LT CD8 et les NK, son rôle précis dans les LT CD4 reste peu connu. D'un point de vue moléculaire, nous avons pu prouver, par des techniques d'Immuno-Précipitation de la Chromatine (ChIP) et des analyses de gènes rapporteurs, que le FT Eomes est un gène cible direct de Foxo3 dans les LT CD4.[...] / CD4 T cells are extremely plastic, and depending on the cytokines that are present within the microenvironment, they have the ability to differentiate into several subpopulations. This process is finely regulated by the expression of Master Regulator of each lineage such as T-Bet, GATA-3, RORgammaT and Foxp3, that are mandatory for the differentiation of Th1, Th2, Th17 and Treg cells respectively. However, they do not act alone, and several other transcription factors are required to stabilize, amplify and lock CD4 T cell lineages. Each subpopulation of CD4 T cells is highly specialized in the elimination of particular types of pathogen; however, in case of dysregulation of the immune response, they can also be involved in the development of autoimmune diseases. In order to determine how such properties are acquired by pathogenic CD4 T cells, we used the Experimental Autoimmune Encephalomyelitis (EAE) model which mimic Multiple Sclerosis pathology. In this model, we identified two transcription factors, Foxo3 and Eomes, that are critical for the differentiation of a particular and highly pathogenic subset of CD4 T cell. Indeed, Foxo3-deficient mice develop a less severe disease as compared to WT littermate and this decreased disease severity is associated with a decreased proportion of IFN-gamma and GM-CSF producing cells. Transcriptomic analysis of Foxo3KO versus WT CD4 T cells revealed that the most downregulated gene within Foxo3KO CD4 T cells is Eomes, which is essential for/to the acquisition of cytotoxic functions and production of IFN-gamma by NK and CD8 T cells. At the molecular level, using Chromatin Immuno-Precipitation experiments and Luciferase assays, we showed that Eomes is a direct target gene of Foxo3 in CD4 T cells. Then, in order to determine which of the downregulated gene is responsible for the decreased production of IFN-gamma and GM-CSF, we decided to overexpress Eomes in Foxo3KO CD4 T cells. Eomes overexpression restored IFN-gamma and, to a lesser extent, GM-CSF production by CD4 T cells, thus indicating that Eomes is involved in IFN-gamma and GM-CSF regulation in CD4 T cells.[...]

Mice with human immune systems, generated by transplanting human CD34+ cells into immunodeficient mice, are essential tools for studying phenomena unique to the human immune system or poorly reproduced in existing mouse models. Human immune tolerance induction, function and autoimmunity have been poorly modeled in conventional murine models, which often have poor predictive value for preclinical development. Models that allow the study of human immune cells with the reproducibility and flexibility of small animal models are required. In our lab, humanized mouse models have been used to study preclinical protocols for human xenotolerance induction and to better understand the immunological underpinnings of human autoimmunity. These are each areas of critical unmet medical need. Xenotolerance-inducing protocols may be necessary to allow long-term survival of a transplanted pig organ in a human patient, and, with more than 113,000 Americans currently waiting for a life-saving organ, the need to expand the pool available for transplantation is urgent. Additionally, clinical options for patients with autoimmune diseases are limited. Currently, most patients with autoimmunity are only diagnosed after significant immune damage of target organs. Predicting who will develop autoimmunity – and who will not – before damage occurs would be very useful but is currently very difficult. Small animal models that can better help us understand how human autoimmunity develops could help us develop protocols for early detection and even prevention. We have developed a personalized immune model to study the development of an individual patient’s immune system in a transplanted mice to better understand immune abnormalities that underlie autoimmunity. We have used existing humanized mouse models to answer important questions related to human xenotolerance induction and autoimmunity, but in the studies described here we have worked to extend our capacity to use these models to study human T cell development and peripheral function. We would like to be able to study both the initial selection of T cell receptors (TCRs) in the thymus based on their ability to recognize antigen in the context of presenting MHC without reacting unduly to self-antigen, as well as in the periphery, where T cells interact with peripheral antigen-presenting cells (APCs) to maintain homeostasis and respond to antigen. First, we have incorporated TCR transgenesis into our humanized mouse models to allow greater precision in studying thymic selection in our humanized mice. Developing a system for this would allow us to study in greater detail mechanisms of human xenotolerance induction, including confirming that a swine thymus can support positive selection of T cells with human-restricted TCRs to allow a future xenotransplantation patient to maintain immune competence, while also robustly tolerizing human T cells expressing pig-reactive TCRs. We will also expand this system to study the thymic selection of human T cells with autoreactive TCRs to better understand mechanisms of central tolerance and understand how they fail in autoimmunity. Finally, while processes of thymic selection are critical for human T cell development and function, peripheral interactions also have a large impact on human T cell function and homeostasis and may contribute to the development of autoimmunity. For these interactions to occur appropriately requires robust engraftment and reconstitution of APCs, especially of myeloid and B cell lineages, in transplanted immunodeficient mice. APC reconstitution tends to be suboptimal in humanized mice and is even more so in mice transplanted with patient-derived CD34+ cells. Better characterization of human APC populations and their progenitors could allow us to develop approaches to improve long-term human APC reconstitution in patient-derived humanized mice, allowing us to more fully model patient peripheral T cell function.

Abstract not available

Systemic lupus erythematosus (SLE) and Sj?gren?s syndrome (SS) are both heterogeneous autoimmune diseases with strong B cell aspects. A proportion of SLE and SS patients exhibit elevated serum BAFF (B cell activating factor of the TNF family); BAFF plays a key role in B cell homeostasis, survival and tolerance. BAFF transgenic (Tg) mice develop nephritis and salivary gland destruction that resemble aspects of SLE and SS respectively. Autoimmune disease development in BAFF Tg mice correlates with marginal zone (MZ) B cell expansion and the abnormal presence of MZ-like B cells outside of the spleen. The role of MZ B cells in BAFF induced autoimmune disease was analysed by crossing BAFF Tg mice with Lymphotoxin-β knockout mice (creating LTβ-BTg mice) which lack most peripheral lymph nodes, and also lack MZ B cells as a result of disrupted splenic architecture. LTβ-BTg mice were not protected against nephritis but exhibited reduced salivary gland infiltration and destruction. Indicating that the development of sialadenitis but not nephritis in BAFF Tg mice is MZ B cell dependent. Nephritis development in LTβ-BTg mice was associated with the detection of B-1 B cells in the inflamed kidneys. As B-1a B cell survival is dependent on the spleen, the contribution of B-1a B cells to nephritis development in BAFF Tg mice was assessed by crossing BAFF Tg mice to congenitally asplenic Hox11-/- mice (creating Hox11 -BTg mice). The absence of a spleen and B-1a B cells in Hox11-BTg mice delayed the nephritis development. In contrast, splenectomy of BAFF Tg mice at 12 weeks of age did not alter nephritis onset. In these mice B-1a B cells persisted in the peritoneal cavity and MZ-like B cells were detected in the periphery 8 months after surgery. In summary, nephritis development in BAFF Tg mice is unaltered by the absence of MZ B cells, but delayed in the absence of a spleen, MZ and B-1a B cells. Thus, B-1a and B-1b B cells may be potential targets for the treatment of nephritis in SLE patients with elevated BAFF.

<p>The existence of immune self-tolerance allows the immune system to mount responses against infectious agents, but not against self-molecular constitutes. Although self-tolerance is a robust phenomenon, in some individuals as well as in experimental models, the self-tolerance breaks down and as a result, a self-destructive autoimmune disease emerges. The underlying mechanisms for the development of autoimmune diseases are not known, but genetic, environmental and immunological factors are suggested to be involved. In this thesis, we used murine mercury-induced autoimmunity to test this suggestion.</p><p>In susceptible mice mercuric chloride induces a systemic autoimmune disease characterized by increased serum levels of IgG1 and IgE, production of anti-nucleolar autoantibodies (ANolA) and formation of renal IgG deposits. In contrast, in resistant DBA/2 (H-2^d) mice, none of these characteristics develop after exposure to mercury. By crossing and backcrossing mercury-resistant DBA/2 mice to mercury susceptible strains, we found that the resistance was inherited as a dominant trait in F1 hybrids and that one gene or a cluster of genes located in the H-2 loci determined the resistance to ANolA production, whereas resistance to the other characteristics was found to be controlled by two or three non-H-2 genes.</p><p>We further put forward the “cryptic peptide hypothesis” to investigate whether mercury and another xenobiotic metal use similar pathway(s) to induce the H-2 linked production of ANolA. We found that while mercury stimulated ANolA synthesis in all H-2 susceptible (H-2^s, H-2^q and H-2^f) mouse strains, silver induced only ANolA responses in H-2^s and H-2^q mice, but not in H-2^fmice. Further studies showed that the resistance to silver-induced ANolA production in H-2^fmice was inherited as a dominant trait.</p><p>We next tested the proposition that mercury induces more adverse immunological effects in mouse strains, which are genetically prone to develop autoimmune diseases, using tight-skin 1 mice, an animal model for human Scleroderma. It was found that in this strain, mercury induced a strong immune activation with autoimmune characteristics, but did not accelerate the development of dermal fibrosis, a characteristic in Tsk/1 mice.</p><p>Finally we addressed the Th1/Th2 cross-regulation paradigm by examining if a Th1-type of response could interact with a Th2-type of response if simultaneous induced in susceptible mice. Our findings demonstrated that mercury-induced autoimmunity (Th2-type) and collagen-induced arthritis (CIA) (Th1-type) can interact in a synergistic, antagonistic or additive fashion, depending on at which stage of CIA mercury is administered.</p>

Activation of immunity to self-antigens is the goal in cancer immunotherapy, whereas blocking such responses is the goal in autoimmune disease. Thus, it is not surprising that investigation into cancer immunotherapy might also produce insights for the treatment of autoimmune disease. Heat shock protein, gp96, based therapies lead to the robust activation of CD8+ cytotoxic T cells that can slow tumor growth in 60-70% of mice, but only lead to the elimination of tumors in 30-40% of animals. The primary goal of the current studies was to understand why vaccination with a secreted gp96 vaccine was not efficacious in a larger proportion of animals, and identify combination therapies that enhanced the anti-tumor activity of gp96-Ig vaccination. It was found that in mice bearing established tumors, some mice responded well to vaccination with gp96-Ig, and that the induction of CD8+ T cells was found to correlate with tumor rejection; indicating that the proportion of mice that failed to reject tumors had established mechanisms of tumor-mediated suppression of anti-tumor immunity. The mechanism of this suppression was found to differ between various tumor models, so combination therapy sought to amplify CD8+ T cell responses directly, rather than by indirectly inhibiting suppressive factors induced by established tumors. It was found that antibody-based therapies leading to the stimulation of TNFRSF25, a powerful T cell co-stimulatory receptor, caused synergistic expansion of tumor-specific T cells when given in combination with gp96-Ig vaccination and led to enhanced rejection of multiple tumor types. Interestingly, TNFRSF25 agonistic antibodies were also found to directly stimulate the proliferation of natural CD4+FoxP3+ regulatory T cells. This activity was found to be beneficial in the prevention of allergic lung inflammation when administered prior to antigen challenge. These studies have therefore identified the conditions required for successful tumor elimination following gp96-Ig vaccination, and discovered that a TNFRSF25 agonistic antibody may be used to enhance anti-tumor immunity induced by gp96-Ig. These studies have also identified TNFRSF25 stimulation as the most powerful, and physiologically relevant, method to selectively induce Treg proliferation in vivo ever discovered, with important consequences for the treatment of autoimmune inflammation.

Type 1 diabetes (T1D) is a chronic autoimmune disease in which the insulin producing β-cells in the pancreatic islets of Langerhans are selectively attacked by the immune system. The β-cells are destroyed resulting in a reduced or eliminated insulin production, which in turn lead to a high blood glucose level. The non-obese diabetic (NOD) mouse is the most commonly used animal model for human T1D. NOD mice develop diabetes spontaneously through a process that closely resembles the human pathogenesis. In both humans and the NOD mouse, disease is caused by a combination of genetic and environmental factors. In the NOD mouse, more than 30 insulin-dependent diabetes (Idd) loci on 15 chromosomes have been linked to disease susceptibility, however, most of the Idd-regions lack identification of a disease associated gene. B cells are required for T1D development, although the underlying mechanisms are not fully revealed. The aim of this thesis was to dissect B cell-related immune deviations in the NOD mouse, including the underlying genetics of these traits. The TACI receptor binds two ligands, i.e. the cytokines BAFF and APRIL.TACI ligation by APRIL mediates class switch, drives plasma cell differentiation and increases immunoglobulin production. In Paper I, a novel NOD-specific B cell-related trait was identified, i.e. the increased percentage of TACIhigh-expressing splenic B cells, by comparing NOD mice with non-autoimmune disease prone C57BL/6 mice. To investigate if the described TACI trait was controlled by genes linked to any Idd-region, an Idd-focused linkage analysis was performed. The TACI-trait mapped to regions on chromosome 1 and 8, more specifically to the vicinity of the Idd5.4 and Idd22. Interestingly, the linkage to Idd22 was explained by mice ≥61 days of age, suggesting a temporal genetic regulation of TACI expression possibly influenced by the ongoing autoimmune process. In Paper II, the linkage of the TACI trait to chromosome 1 and 8 was confirmed by analyzing the percentage of TACIhigh-expressing B cells in congenic NOD.C1/Idd22 mice. Moreover, the functional consequence of TACI upregulation was investigated, with the focus on plasma cell development and immunoglobulin production. NOD splenic B cells stimulated with APRIL displayed increased numbers of plasma cells and produced higher amounts of IgG and IgA compared to B cells from C57BL/6 mice. Thus, the TACI upregulation on NOD B cells possibly contribute to a B cell compartment which is more disposed to plasma cell differentiation and isotype switch. NOD mice display enhanced and prolonged immune response towards several antigens, including non-self immunoglobulins. In Paper III, the genetic factor(s) controlling the altered immune response against a BALB/c derived monoclonal antibody were dissected. Significant linkage to the Idd1/Idd24, Idd12, and Idd18.1 regions as well as to a proximal region on chromosome 2 (33.5 Mb) was detected. The linkage to Idd1/24 was verified by analyzing a set of H2-congenic NOD and C57BL/6 mice, and the linked region was narrowed down to ~8 Mb. Candidate gene analysis revealed a significant difference in the transcription of the H2-O/DO molecule. This suggests that multiple mechanisms contribute to the loss of immune response control, including an altered MHC class II peptide loading on NOD B cells. In Paper IV, a novel B cell intrinsic receptor for IgM and IgG was revealed. The receptor appeared to be more abundant in NOD mice compared to C57BL/6 mice, as the level of extramembranous IgG monomers and IgM pentamers on peripheral blood B cells from NOD mice was significantly higher compared to C57BL/6 mice. In addition, analysis of immune complex binding using IgG- or IgM-opsonized bacterial particles revealed a higher degree of binding in NOD mice compared with C57BL/6 mice. The enhanced capture of immunoglobulins and immune complexes could thus contribute to the development of T1D by altering normal B cell functions such as activation and immune complex transportation.