Prostatein (or rat prostatic steroid binding protein) is a major autoantigen in experimental autoimmune prostatitis

Experimental autoimmune prostatitis (EAP) is a disease that could be considered an experimental model of human non-bacterial prostatitis. In this experimental model, male rats are intradermally immunized with a saline extract of male sex accessory glands (RAG) in an adequate adjuvant. The prostatitis observed in the immunized animals develops as a consequence of the immune response against RAG antigens, and the histological lesion is strikingly similar to the pattern of prostatic inflammation observed in the human disease. In this study, we purified one of the prostatic autoantigens recognized by the autoantibodies in our model. Amino acid sequence analysis identified the purified protein as prostatein or rat prostatic steroid binding protein, a member of the uteroglobin superfamily. Prostatein was recognized not only by the humoral autoimmune response, but also by the cellular autoimmune response. Certainly, the DTH response and lymph node cell proliferative assays against prostatein in immunized animals yielded positive results. Prostatein is not only the target of the autoimmune response in animals immunized with the whole extract, but also an inducing antigen of the disease. Purified prostatein, when incorporated to an adequate adjuvant, elicited cellular and humoral autoimmune response and lesion in the prostate gland. The identification of one of the target antigens in autoimmune prostatitis has provided a further refinement and characterization of our model, which could serve for a better understanding of the aetiology, pathogenesis and pathophysiology of non-bacterial prostatitis.     

树突细胞与哮喘Th1/Th2失衡

特应性哮喘患者以Th2免疫反应为主,导致气道炎症,Th1／Th2失衡是特庆性哮喘重要的免疫病理机制,树突细胞（DCs）中肺部主要抗原递呈细胞,不但可以介志对吸入抗原初始的免疫反应,活化辅助性T细胞,而且在可以决定T细胞的分化方向,维持哮喘Th2免疫反应和Th1／Th2失衡机制中发挥重要作用而日益受到重视。本文就近年来对特应性哮喘免疫病理机制中DCs对Th1／Th2失衡影响认识作一综述。     

Mycobacterium vaccae administration during allergen sensitization or challenge suppresses asthmatic features

BACKGROUND AND OBJECTIVE: The hygiene hypothesis suggests that a lack of bacterial infections would favour the development of allergic disease. For this reason, bacteria or their components can be used as potential treatment for allergic asthma. We investigated whether heat-killed Mycobacterium vaccae is either able to suppress the induction of allergic asthma or able to suppress already established allergic asthma. METHODS: Mice were sensitized with ovalbumin (OVA)/alum on days 0 and 14. Thereafter, mice were challenged on days 35, 39 and 42 by inhalation of either OVA or saline aerosols. M. vaccae-treated mice received an injection with 106, 107 or 108 CFU heat-killed M. vaccae on days 0 and 14 or 107 CFU on days 35 and 39. On day 43, the airway responsiveness of the mice to increasing concentrations of methacholine was assessed, blood was withdrawn to measure serum parameters, and lung lavage was performed to detect cytokines and inflammatory cell number. RESULTS: Treatment of OVA-sensitized mice with 107 CFU M. vaccae either during sensitization or challenge suppresses airway hyper-responsiveness, airway eosinophilia and IL-5 production after OVA challenge. The increases in OVA-specific serum IgE and in IL-4 by respiratory challenges with OVA were only diminished after M. vaccae treatment (107 CFU) during sensitization. CONCLUSIONS: Heat-killed M. vaccae prevents allergic and asthmatic manifestations in a mouse model and, more importantly, M. vaccae treatment during challenge suppresses features of asthma, which opens up possibilities for new therapeutic interventions.     

Exacerbated Th2-mediated airway inflammation and hyperresponsiveness in autoimmune diabetes-prone NOD mice: a critical role for CD1d-dependent NKT cells

The NOD mouse has proved to be a relevant model of insulin-dependent diabetes mellitus, closely resembling the human disease. However, it is unknown whether this strain presents a general biastoward Th1-mediated autoimmunity or remains capable of mounting complete Th2-mediated responses. Here, we show that NOD mice have the capacity to develop a typical Th2-mediated disease, namely experimental allergic asthma. In contrast to what might have been expected, they even developed a stronger Th2-mediated pulmonary inflammatory response than BALB/c mice, a strain that shows a typical Th2 bias in this model. Thus, after allergen sensitization and intra-nasal challenge, the typical features of experimental asthma were exacerbated in NOD mice, including enhanced bronchopulmonary responsiveness, mucus production and eosinophilic inflammation in the lungs as well as specific IgE titers in serum. These hallmarks of allergic asthma were associated with increased IL-4, IL-5, IL-13 and eotaxin production in the lungs, as compared with BALB/c mice. Notwithstanding their quantitative and functional defect in NOD mice, CD1d-dependent NKT cells contribute to aggravate the disease, since in OVA-immunized CD1d(-/-) NOD mice, which are deficient in this particular T cell subset, airway eosinophilia was clearly diminished relative to NOD littermates. This is the first evidence that autoimmune diabetes-prone NOD mice can also give rise to enhanced Th2-mediated responses and might thus provide a useful model for the study of common genetic and cellular components, including NKT cells that contribute to both asthma and type 1 diabetes.     

Analysis of mercury-induced immune activation in nonobese diabetic (NOD) mice

In susceptible mice, the heavy metal ion mercury is able to induce a strong immune activation, which resembles a T helper 2 (Th2) type of immune response and is characterized by a polyclonal B cell activation, formation of high levels of IgG1 and IgE antibodies, production of autoantibodies of different specificities and development of renal IgG deposits. In the present study, we analysed the in vivo effects of mercury in nonobese diabetic (NOD) mice, which is believed to develop a spontaneous Th1 cell-mediated autoimmune diabetes similar to type 1 diabetes in humans. Three weeks of treatment with mercury induced a strong Th2 like immune/autoimmune response in NOD mice. This response was characterized by an intensive increase in splenic IgG1 antibody secreting cells, a marked elevation in serum IgE levels, a substantial increase in splenic IL-4 mRNA, but a significant decrease in splenic IFN-gamma mRNA. Mercury-induced IgG1 antibodies were mainly against ssDNA, TNP and thyroglobulin, but not against nucleolar antigen. Moreover, mercury-injected NOD mice developed high titres of IgG1 deposits in the kidney glomeruli. We further tested if the generated Th2 response could interfere with the development of insulitis and diabetes in NOD mice. We found that three weeks of treatment with mercury was also able to significantly suppress the development of insulitis and postpone the onset of diabetes in these mice. Thus, mercury-induced immune activation can counter-regulate the Th1 cell-mediated autoimmune responses and confer a partial protection against autoimmune diabetes in NOD mice.     

Inhibition of diabetes in NOD mice by human pregnancy factor

Clinical symptoms of Th1 mediated autoimmune diseases regress in many patients during pregnancy. A prominent feature of pregnancy is the presence of human chorionic gonadotrophin hormone (hCG) in blood and urine. In this report we tested the effect of clinical grade hCG (c-hCG) on the development of diabetes, a Th1 mediated autoimmune disease, in nonobese diabetic (NOD) mice. We show that treatment of NOD mice with c-hCG before the onset of clinical symptoms lowered the increased blood glucose levels, reversed the established inflammatory infiltrate of pancreatic tissue, and profoundly inhibited the development of diabetes for prolonged time. c-hCG also induced profound inhibition of the functional activity (i.e. production of IFN-γ) of Th1 cells. Transfer of spleen cells from c-hCG-treated NOD mice into immunocompromised NOD.SCID mice inhibited the development of diabetes in these otherwise nontreated mice. This shows that the treatment of the donor NOD mice induced persistent changes in the immune system. The antidiabetic activity of c-hCG was not caused by heterodimeric hCG or its subunits. Instead, this antidiabetic activity resided in a fraction of c-hCG preparation that contains a 400–2000 Dalton natural (immuno) modulatory pregnancy factor (NMPF).     

Food allergy promotes a Th2/Th17 response that drives house dust mite-induced allergic airway inflammation in humanized mice

Food allergy is related to increasing risk of the development of allergic asthma, but the precise interplay between sensitization to different allergens in different compartments of the body is not fully understood. The aim of this study was to develop a novel humanized murine model of mixed food and respiratory allergy that recapitulates the human anaphylactic response and to more clearly understand the impact of food allergies on asthma. Immunodeficient mice transferred with peripheral blood mononuclear cells (PBMCs) from donors with peanut and house dust mite (HDM) allergy were exposed and challenged to peanut. Between peanut exposure and challenge, mice were intranasally treated to HDM. Allergic parameters were analyzed. Allergen-specific immunoglobulin (Ig)E in sera could only be measured in mice treated with peripheral blood mononuclear cells (PBMCs) plus allergen. A preceding peanut exposure increased IgE levels, histamine release, bronchial hyper-responsiveness and lung inflammation. Recruitment of inflammatory cells to the airways was aggravated associated with an enhanced T helper type 2 (Th2)/Th17 cytokine secretion when the two allergies were present. A preceding peanut exposure amplifies allergic asthma in this humanized model, which may contribute to the understanding of underlying immunological mechanism of polysensitization occurring in allergic individuals and evaluation of therapeutic interventions.     

Differential capacity of CD8α+ or CD8α− dendritic cell subsets to prime for eosinophilic airway inflammation in the T-helper type 2-prone milieu of the lung

BACKGROUND: Different subsets of dendritic cells (DCs), identified in mouse spleen by their differential expression of CD8 alpha, can induce different T-helper (Th) responses after systemic administration. CD8 alpha(-) DCs have been shown to preferentially induce Th type 2 (Th2) responses whereas CD8 alpha(+) DCs induce Th1 responses. OBJECTIVE: To study if these DC subsets can still induce different Th responses in the Th2-prone milieu of the lung and differentially prime for eosinophilic airway inflammation, typical of asthma. METHODS: Donor mice first received daily Flt3L injections to expand DC numbers. Purified CD8 alpha(+) or CD8 alpha(-) splenic DCs were pulsed with ovalbumin (OVA) or phosphate-buffered saline and injected intratracheally into recipient mice in which carboxyfluorescein diacetate succinimidyl ester-labelled OVA-specific T cell receptor transgenic T cells had been injected intravenously 2 days earlier. T cell proliferation and cytokine production of Ag-specific T cells were evaluated in the mediastinal lymph nodes (MLNs) 4 days later. The capacity of both subsets of DCs, to prime for eosinophilic airway inflammation was determined by challenging the mice with OVA aerosol 10 days later. RESULTS: CD8 alpha(-) DCs migrated to the MLN and induced a vigorous proliferative T cell response accompanied by high-level production of IL-4, IL-5, IL-10 and also IFN-gamma during the primary response and during challenge with aerosol, leading to eosinophilic airway inflammation. In the absence of migration to the MLN, CD8 alpha(+) DCs still induced a proliferative response with identical levels of IFN-gamma but reduced Th2 cytokines compared with CD8 alpha(-) DCs, which led to weak eosinophilic airway inflammation upon OVA aerosol challenge. Unpulsed DCs did not induce proliferation or cytokine production in Ag-specific T cells. CONCLUSION: CD8 alpha(-) DCs are superior compared with CD8 alpha(+) DCs in inducing Th2 responses and eosinophilic airway inflammation in the Th2-prone environment of the lung.     

Engagement of human monocyte-derived dendritic cells into interleukin (IL)-12 producers by IL-1beta + interferon (IFN)-gamma

Dendritic cells (DCs) are potent antigen-presenting cells and can induce tumour- or pathogen-specific T cell responses. For adoptive immunotherapy purposes, immature DCs can be generated from adherent monocytes using granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-4, and further maturation is usually achieved by incubation with tumour necrosis factor (TNF)-alpha. However, TNF-alpha-stimulated DCs produce low levels of IL-12. In this study, we compared the effects of TNF-alpha, interferon (IFN)-gamma, IL-1beta or IFN-gamma + IL-1beta on the phenotypic and functional maturation of DCs. Our results show that IFN-gamma, but not IL-1beta, augmented the surface expression of CD80, CD83 and CD86 molecules without inducing IL-12 production from DCs. However, IL-1beta, but not IFN-gamma, induced IL-12 p40 production by DCs without enhancing phenotypic maturation. When combined, IFN-gamma + IL-1beta treatment profoundly up-regulated the expression of CD80, CD83, CD86 and major histocompatibility complex (MHC) class II antigens. Furthermore, IFN-gamma + IL-1beta-treated DCs produced larger amounts of IL-12 and induced stronger T cell proliferation and IFN-gamma secretion in primary allogeneic mixed lymphocyte reaction (MLR) than did TNF-alpha-treated DCs. Our results show that IFN-gamma + IL-1beta induced human monocyte-derived DCs to differentiate into Th1-prone mature DCs.     

Molecular mimicry as an inducing trigger for CNS autoimmune demyelinating disease

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that affects about 0.1% of the worldwide population. This deleterious disease is marked by infiltration of myelin-specific T cells that attack the protective myelin sheath that surrounds CNS nerve axons. Upon demyelination, saltatory nerve conduction is disrupted, and patients experience neurologic deficiencies. The exact cause for MS remains unknown, although most evidence supports the hypothesis that both genetic and environmental factors contribute to disease development. Epidemiologic evidence supports a role for environmental pathogens, such as viruses, as potentially key contributors to MS induction. Pathogens can induce autoimmunity via several well-studied mechanisms with the most postulated being molecular mimicry. Molecular mimicry occurs when T cells specific for peptide epitopes derived from pathogens cross-react with self-epitopes, leading to autoimmune tissue destruction. In this review, we discuss an in vivo virus-induced mouse model of MS developed in our laboratory, which has contributed greatly to our understanding of the mechanisms underlying molecular mimicry-induced CNS autoimmunity.     

Human dendritic cells transfected with allergen-DNA stimulate specific immunoglobulin G4 but not specific immunoglobulin E production of autologous B cells from atopic individuals in vitro

Atopic/allergic diseases are characterized by T helper 2 (Th2)-dominated immune responses resulting in immunoglobulin E (IgE) production. DNA-based immunotherapies have been shown to shift the immune response towards Th1 in animal models. In further studies we showed that human dendritic cells (DC) transfected with allergen-DNA are able to stimulate autologous CD4(+) T cells from atopic individuals to produce Th1 instead of Th2 cytokines and to activate interferon-gamma (IFN-gamma)-producing CD8(+) T cells. The aim of this study was to analyse whether DC transfected with allergen-DNA are also able to influence immunoglobulin production of B cells from atopic donors. For this purpose, human monocyte-derived DC from grass-pollen allergic donors were transfected with an adenovirus encoding the allergen Phleum pratense 1 and cocultured with B cells, autologous CD4(+) T cells, and CD40 ligand-transfected L-cells. B cells receiving help from CD4(+) T cells stimulated with allergen-transfected dendritic cells produced more allergen-specific IgG4 compared to stimulation with allergen protein pulsed DC or medium, while total IgG4 production was not affected. In contrast, specific IgE production was not enhanced by stimulation with allergen-DNA transfected DC compared to medium and inhibited compared to allergen protein-pulsed DC with similar effects on total IgE production in vitro. Allergen-DNA transfected dendritic cells are able to direct the human allergic immune response from Th2-dominance towards Th1 and Tc1 also resulting in decreased IgE and increased IgG4 production.     

Inhibition of human allergic T-helper type 2 immune responses by induced regulatory T cells requires the combination of interleukin-10-treated dendritic cells and transforming growth factor-β for their induction

BACKGROUND: In grass pollen-allergic individuals, T cell anergy can be induced by IL-10-treated dendritic cells (IL-10-DC) resulting in the suppression of T helper type 1 (Th1) as well as Th2 cells. This study was performed to analyse whether such IL-10-DC-treated T cells are able to act as regulatory T cells (Treg) suppressing the function of other T cells in the periphery. As transforming growth factor (TGF)-beta is also a potential inducer of Treg, we additionally analysed the inhibitory capacity of TGF-beta-treated T cells in this system. MATERIALS AND METHODS: Freshly isolated CD4+ or CD4+ CD25- T cells from grass pollen-allergic donors were stimulated with autologous mature monocyte-derived allergen-pulsed DC in the presence or absence of T cells previously cultured with IL-10-DC- and/or TGF-beta. RESULTS: Anergic T cells induced by allergen-pulsed IL-10-treated DC or allergen-pulsed DC and TGF-beta enhanced IL-10 production and strongly inhibited IFN-gamma production of freshly prepared peripheral CD4+ or CD4+ CD25- T cells while proliferation and Th2 cytokine production were only slightly reduced. The combination of allergen-pulsed IL-10-treated DC and TGF-beta had an additional effect leading to a significant suppression also of Th2 cytokine production and proliferation. Suppression was not antigen-specific and was mainly mediated by cell-to-cell contact and by the molecule-programmed death-1 and only partially by CTLA-4, TGF-beta and IL-10. CONCLUSION: These data demonstrate that regulatory T cells that also suppress Th2 cytokine production are induced by two signals: TGF-beta and IL-10-DC. This is of importance for the regulation of allergic immune responses and might be exploited for future therapeutic strategies for allergic diseases.     

Nasal tolerance in experimental autoimmune myasthenia gravis (EAMG): induction of protective tolerance in primed animals

Nasal administration of μg doses of acetylcholine receptor (AChR) is effective in preventing the development of B cell-mediated EAMG in the Lewis rat, a model for human MG. In order to investigate whether nasal administration of AChR modulates ongoing EAMG, Lewis rats were treated nasally with AChR 2 weeks after immunization with AChR and Freund's complete adjuvant. Ten-fold higher amounts of AChR given nasally (600 μg/rat) were required to ameliorate the manifestations of EAMG compared with the amounts necessary for prevention of EAMG. In lymph node cells from rats receiving 600 μg/rat of AChR, AChR-induced proliferation and interferon-gamma (IFN-γ) secretion were reduced compared with control EAMG rats receiving PBS only. The anti-AChR antibodies in rats treated nasally with 600 μg/rat of AChR had lower affinity, reduced proportion of IgG2b and reduced capacity to induce AChR degradation. Numbers of AChR-reactive IFN-γ and tumour necrosis factor-alpha (TNF-α) mRNA-expressing lymph node cells from rats treated nasally with 600 μg/rat of AChR were suppressed, while IL-4, IL-10 and transforming growth factor-beta (TGF-β) mRNA-expressing cells were not affected. Collectively, these data indicate that nasal administration of AChR in ongoing EAMG induced selective suppression of Th1 functions, i.e. IFN-γ and IgG2b production, but no influence on Th2 cell functions. The impaired Th1 functions may result in the production of less myasthenic anti-AChR antibodies and contribute to the amelioration of EAMG severity in rats treated with AChR 600 μg/rat by the nasal route.     

Deficient arginase II expression without alteration in arginase I expression attenuated experimental autoimmune encephalomyelitis in mice

In the past there have been a multitude of studies that ardently support the role of arginase II (Arg II) in vascular and endothelial disorders; however, the regulation and function of Arg II in autoimmune diseases has thus far remained unclear. Here we report that a global Arg II null mutation in mice suppressed experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. During EAE, both Arg I and Arg II were induced in spinal cords, but only Arg II was induced in spleens and splenic dendritic cells (DCs). DC activation by lipopolysaccharide (LPS), CD40L or TLR8 agonist significantly enhanced Arg II expression without affecting Arg I expression. Conversely, DC differentiating cytokines [IL‐4 and granulocyte macrophage‐colony‐stimulating factor (GM‐CSF)] yielded opposite effects. In addition, Arg I and Arg II were regulated differentially during Th1 and Th17 cell polarization. Arg II deficiency in mice delayed EAE onset, ameliorated clinical symptoms and reduced myelin loss, accompanied by a remarkable reduction in the EAE‐induced spinal cord expression of Th17 cell markers (IL‐17 and RORγt). The abundance of Th17 cells and IL‐23⁺ cells in relevant draining lymph nodes was significantly reduced in Arg II knockout mice. In activated DCs, Arg II deficiency significantly suppressed the expression of Th17‐differentiating cytokines IL‐23 and IL‐6. Interestingly, Arg II deficiency did not lead to any compensatory increase in Arg I expression in vivo and in vitro. In conclusion, Arg II was identified as a factor promoting EAE likely via an Arg I‐independent mechanism. Arg II may promote EAE by enhancing DC production of Th17‐differentiating cytokines. Specific inhibition of Arg II could be a potential therapy for multiple sclerosis.     

Allergological implication of the quaternary hexameric structure of the cockroach allergen Per a 3

Background Cockroach allergens play a very important role in allergic diseases, especially asthma. The major allergen of the American cockroach (Periplaneta americana), Per a 3, naturally occurs as isoforms of hexamers. Objective The aim of this study was to investigate whether the hexameric structures of Per a 3 influence their allergenicity and immunogenicity. Methods Therefore, we compared the different effects of native hexamers and dissociated monomers of cockroach haemolymph (HL), containing almost only Per a 3 proteins (HL‐Per a 3), on proliferation and T‐helper type 1 (Th1)/Th2 cytokine production of human CD4⁺ T cells in co‐culture with allergen‐pulsed monocyte‐derived autologous dendritic cells (DC) as well as the leukotriene release of basophils. Results In P. americana‐sensitized and non‐sensitized donors the HL‐Per a 3 monomers were internalized faster by immature DC and induced higher proliferation and IFN‐γ production than the hexamers. While in non‐sensitized donors IL‐4 and IL‐5 as well as IL‐10 production were also increased after stimulation with monomeric HL‐Per a 3‐pulsed DC, Th2 cytokine and IL‐10 production were only enhanced in P. americana‐sensitized donors using hexameric HL‐Per a 3‐pulsed DC. Furthermore, in the leukotriene release assay the monomers were less effective than the hexamers. Conclusion Our data indicate that the quaternary structure can influence both allergenicity and immunogenicity, also depending on the sensitization status. The monomeric variant of Per a 3 allergens could be a possible candidate for a specific immunotherapy because the IgE‐mediated allergic reaction and the Th2‐inducing capacity are diminished while the Th1‐inducing capacity is retained.     

Prior Bordetella pertussis infection modulates allergen priming and the severity of airway pathology in a murine model of allergic asthma

BACKGROUND: It has been proposed that T helper (Th)2-driven immune deviation in early life can be countered by Th1 inducing childhood infections and that such counter-regulation can protect against allergic asthma. OBJECTIVE: To test whether Th1-inducing infection with Bordetella pertussis protects against allergic asthma using well-characterized murine models. METHODS: Groups of mice were sensitized to ovalbumin (OVA) in the presence or absence of B. pertussis, a well-characterized Th1 inducing respiratory infection. Immunological, pathological and physiological parameters were measured to assess the impact of infection on immune deviation and airway function. RESULTS: We demonstrate that OVA sensitization does not affect the development of B. pertussis-specific immune responses dominated by IgG2a and IFN-gamma and does not impair Th1-mediated clearance of airway infection. In contrast, B. pertussis infection at the time of sensitization modulated the response to OVA and significantly reduced total serum and OVA-specific IgE. The pattern of cytokine responses, in particular OVA-specific IL-5 responses in the spleen was also modulated. However, B. pertussis did not cause global suppression as IL-10 and IL-13 levels were enhanced in OVA-stimulated spleen cell cultures and in lavage fluid from infected co-sensitized mice. Histopathological examination revealed that B. pertussis infection prior to OVA sensitization resulted in increased inflammation of bronchiolar walls with accompanying hyperplasia and mucous metaplasia of lining epithelia. These pathological changes were accompanied by increased bronchial hyper-reactivity to methacholine exposure. CONCLUSION: Contrary to the above premise, a Th1 response induced by a common childhood infection does not protect against bronchial hyper-reactivity, but rather exacerbates the allergic asthmatic response, despite modulation of immune mediators.     

Mechanisms of Mycobacterium avium-induced resistance against insulin-dependent diabetes mellitus (IDDM) in non-obese diabetic (NOD) mice: role of Fas and Th1 cells

NOD mice spontaneously develop autoimmune diabetes. One of the manipulations that prevent diabetes in NOD mice is infection with mycobacteria or immunization of mice with mycobacteria-containing adjuvant. Infection of NOD mice with Mycobacterium avium, done before the mice show overt diabetes, results in permanent protection of the animals from diabetes and this protective effect is associated with increased numbers of CD4⁺ T cells and B220⁺ B cells. Here, we investigate whether the M. avium-induced protection of NOD mice from diabetes was associated with changes in the expression of Fas (CD95) and FasL by immune cells, as well as alterations in cytotoxic activity, interferon-gamma (IFN-γ) and IL-4 production and activation of T cells of infected animals. Our data indicate that protection of NOD mice from diabetes is a Th1-type response that is mediated by up-regulation of the Fas–FasL pathway and involves an increase in the cytotoxicity of T cells. These changes are consistent with induction by the infection of regulatory T cells with the ability of triggering deletion or anergy of peripheral self-reactive lymphocytes that cause the autoimmune disease of NOD mice.     

Absence of significant Th2 response in diabetes-prone non-obese diabetic (NOD) mice.

Accumulating evidence suggests that Th1 T cells play a pivotal role in the development of autoimmune diabetes. Conversely, promoting a Th2 response inhibits disease progression. However, it has not been determined whether Th2 cells are regulatory T cells that fail at the time of diabetes development in naive non-diabetic NOD mice. Therefore, in order to evaluate cytokine secretion by spleen and islet infiltrating T cells in NOD mice at different stages of the autoimmune process, we developed an ELISPOT assay that detects IL-2, IL-4, and interferon-gamma (IFN-gamma) secretion in vitro at the single-cell level. We showed that, whatever the age considered, IFN-gamma is predominantly secreted, and that no IL-4-secreting cells are detected in the islets of male and female NOD mice. Spleen cells from 8-week-old female NOD mice, which include regulatory suppressor T cells, do not secrete IL-4, either upon presentation of islet cell antigens in vitro, or after transfer in vivo, but do secrete IFN-gamma. IFN-gamma secretion by T cells from diabetic mice results from CD4 but not CD8 T cells in transfer experiments into NOD/severe combined immunodeficient (SCID) recipients. These results suggest that (i) detection of regulatory CD4 T cells in NOD mice is not paralleled by a Th2 response; (ii) beta cell destruction does not depend on a switch from a Th2 to a Th1-type response; and (iii) CD8 T cells do not participate in induction of diabetes by secreting IFN-gamma.