Diverse adhesion molecules participate in many important responses and thus would be implicated in the pathogenesis of various autoimmune diseases. However, there is little evidence for the role of these molecules in autoimmune insulin-dependent diabetes mellitus. Here we present several lines of evidence suggesting that leukocyte function-associated antigen-1 (LFA-1) and its counter-receptor intercellular adhesion molecules (ICAM-1), one of the most important pairs among these adhesion molecules, are involved in the development of autoimmune diabetes in the non-obese diabetic (NOD) mouse. Immunohistochemical study showed the hyperexpression of ICAM-1 on islet-infiltrating mononuclear cells and vascular endothelium in NOD pancreas. In vivo administration of anti-LFA-1 or anti-ICAM-1 mAb from 5 to 30 (or 12) weeks of age exerted a very strong preventative effect on the development of spontaneous diabetes with a marked reduction of insulitis, whereas both antibodies, even combined to use simultaneously, could not prevent cyclophosphamide-induced diabetes. Adoptive transfer of insulitis and diabetes to young NOD mice following the injection of islet-derived mononuclear cells from diabetic donors was completely blocked by administration of both antibodies to recipients. The present study, therefore, provides the first evidence that immunointervention to LFA-1-ICAM-1 interaction has a strong prophylactic effect on autoimmune diabetes in NOD mice.

The immune mechanisms directly responsible for beta-cell destruction in insulin-dependent diabetes are undefined. We studied the role of MHC class I-restricted T lymphocytes in the development of diabetes in cyclophosphamide (CY)-treated male and untreated female NOD mice (H-2Kd,Db). After administration of CY to 10-wk-old male NOD/Shi/Kbe mice, 37 of 64 (58%) phosphate-buffered saline-injected control mice and 13 of 22 (59%) anti-Kb and 12 of 27 (44%) anti-Db monoclonal antibody (MoAb)-injected mice became diabetic by 14 wk of age, whereas only 3 of 38 (8%) anti-Kd and 2 of 13 (15%) anti-Lyt-2 MoAb-injected mice did. In untreated female NOD/Shi/Kbe mice, 30 of 46 (65%) mice developed spontaneous diabetes by 30 wk of age, whereas none of 9 anti-Kd MoAb-injected mice became diabetic. Immunohistochemical studies showed that islet-infiltrating cells in CY-treated control mice were composed mainly of both L3T4+ and Lyt-2+ T lymphocytes, whereas many L3T4+ and very few Lyt-2+ lymphocytes infiltrated within the islets in anti-Kd MoAb-injected mice. Administration of anti-Lyt-2 MoAb induced the absence of Lyt-2+ T lymphocytes in the islet and spleen. However, anti-Kd MoAb did not change the number of spleen cells or the T-lymphocyte subset and response to concanavalin A. These results suggest that MHC class I Kd-restricted Lyt-2+ T lymphocytes play an important role as direct effector cells in destruction of beta-cells in NOD/Shi/Kbe mice.

Summary. Recent evidence indicates that activated T cells and macrophages play an important role in the induction of insulitis and diabetes in certain strains of mice treated with multiple subdiabetogenic doses of streptozotoein. In the present study, we treated C57BL/6J mice with five daily doses of 40 mg/ml streptozotocin and examined the prophylactic effect of an anti-interleukin 2 receptor monoclonal antibody (PC61). In mice treated with streptozotocin, interleukin 2 receptor-positive mononuclear cells were shown to infiltrate into the islets and soluble interleukin 2 receptors in the sera were significantly increased compared with control mice. The administration of PC61 to the mice attenuated the insulitis, and diminished interleukin 2 receptor-positive cells from islets and soluble interleukin 2 receptors in the sera. Moreover, the administration of PC61 significantly reduced the development of hyperglycaemia shown in these mice (12.8 _+ 1

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The expression of specific T-cell receptor gene segments by T lymphocytes appears to be critically important for the induction of several experimental autoimmune diseases mediated by these cells. We examined whether this situation also applied to non-obese diabetic mice by using various T-cell receptor V beta-specific monoclonal antibodies. No significant age- or sex-related differences were observed in V beta usage by peripheral and splenic T lymphocytes. CD8+ T lymphocytes among the islet-derived mononuclear cells isolated from 20-week-old female non-obese diabetic mice showed heterogeneity of their V beta gene usage. In order to examine the role of T lymphocyte subsets expressing specific T-cell receptor V beta segments in the development of diabetes mellitus, T-cell receptor V beta-specific monoclonal antibodies were administered to 10-week-old male non-obese diabetic mice treated with cyclophosphamide. None of the antibodies used could significantly diminish the incidence of cyclophosphamide-induced diabetes and the severity of insulitis [anti-V beta 3 (11 of 22 mice became diabetic, 50%), anti-V beta 5 (9 of 14, 64%), anti-V beta 8 (9 of 21, 43%), anti-V beta 11 (12 of 23, 52%), anti-V beta 14 (7 of 12, 58%), and anti-V beta 5 + anti-V beta 11 (6 of 12, 50%)] when compared with control mice (12 of 21, 57%). In addition, there were no significant differences in T-cell receptor V beta usage between diabetic and non-diabetic cyclophosphamide-treated mice.(ABSTRACT TRUNCATED AT 250 WORDS)