Essential role for interferon-gamma and interleukin-6 in autoimmune insulin-dependent diabetes in NOD/Wehi mice.

Abstract

Experimental studies in vitro suggest that cytokines are impor- tant mediators in the pathogenesis of autoimmune insulin-de- pendent diabetes mellitus (IDDM).However, there is little evidence for the role ofcytokines in vivo, either in humans or in the spontaneous animal models of IDDM such as the NOD mouse or BB rat.To address this question, we used the model ofcyclo- phosphamide (CYP)-induced autoimmune diabetes in the NOD/Wehi mouse to examine for (a) the production of IFN-'y and IL-6 from isolated islets, and (b) the effect of anti IFN-'y or anti IL-6 monoclonal antibodies on the development of dia- betes.After cyclophosphamide, the majority of these mice de- velop of mononuclear cell infiltrate (insulitis) which by 10-14 d is associated with beta cell destruction.IFN-y activity at low levels (2.7±0.3U/ml) could be detected only in culture super- natants from islets isolated at day 7 post-cyclophosphamide.In contrast, IL-6 activity progressively increased from 457±44 U/ml at day 0 to 6,020±777 U/ml at day 10.Culture of islets with anti-CD3 monoclonal antibody resulted in a significant increase in IFN-'y activity from 41±7 U/ml at day 0 to 812±156 U/ml at day 10.Mice given either anti-IFN-y or anti- IL-6 antibody had a significantly reduced (P < 0.001) incidence of diabetes and especially with IFN-'y, decreased severity of insulitis.We conclude that IFN-y and IL-6 have essential roles in the pathogenesis of pancreatic islet beta cell destruction in this model.(J.Clin.Invest.1991.87:739-742.)Key words: anti-cytokine therapy * pancreatic islet * beta cell the production of IFN-'y and IL-6 from isolated islets, and (b) the effect of cytokine neutralization in vivo with anti-IFN-y and anti-IL-6 antibodies on the development of diabetes. MethodsMice.Female NOD/Wehi mice, aged 70-80 d, were used in all experi- ments.Although insulitis is present in virtually all mice, the incidence of diabetes in female NOD/Wehi mice in contrast to most strains of NOD mice, is < 5% at age 100 d (21).There are no differences between NOD/Wehi and the high-incidence strain, NOD/Lt on the basis of reciprocal skin grafting and allelic enzyme analysis (22).Monoclonal antibodies and cytokines.Monoclonal antibodies to IFN-y (RA-642; hybridoma cells obtained from the American Type Culture Collection, Rockville, MD) and IL-6 (6B4; hybridoma cells kindly provided by Dr. J. Van Snick, Brussels, Belgium) were obtained from ascites produced in CBA-Nu/Nu mice.After partial purification Interferon--y and Interleukin-6 in Autoimmune Diabetes 739