Progression to destructive insulitis in nonobese diabetic (NOD) mice is linked to the failure of regulatory cells, possibly involving T helper type 2 (Th2) cells. Natural killer (NK) T cells might be involved in diabetes, given their deficiency in NOD mice and the prevention of diabetes by adoptive transfer of α/β double-negative thymocytes. Here, we evaluated the role of NK T cells in diabetes by using transgenic NOD mice expressing the T cell antigen receptor (TCR) α chain Vα14-Jα281 characteristic of NK T cells. Precise identification of NK1.1+ T cells was based on out-cross with congenic NK1.1 NOD mice. All six transgenic lines showed, to various degrees, elevated numbers of NK1.1+ T cells, enhanced production of interleukin (IL)-4, and increased levels of serum immunoglobulin E. Only the transgenic lines with the largest numbers of NK T cells and the most vigorous burst of IL-4 production were protected from diabetes. Transfer and cotransfer experiments with transgenic splenocytes demonstrated that Vα14-Jα281 transgenic NOD mice, although protected from overt diabetes, developed a diabetogenic T cell repertoire, and that NK T cells actively inhibited the pathogenic action of T cells. These results indicate that the number of NK T cells strongly influences the development of diabetes.

The nonobese diabetic (NOD) mouse was established as an inbred strain in 1980 and proposed as a model of type I diabetes mellitus (1). By 6-8 wk of age, mononuclear cells start infiltrating the periphery of pancreatic Langerhans' islets of both males and females. Progressive invasion inside the islets occurs later and is correlated with selective destruction of insulin-producing ß cells and with the onset of clinically overt diabetes . Diabetes is first observed at 12 wk of age and strongly predominates in females. By 30 wk of age,^-70% of females have become diabetic, while <20% of males develop overt disease (2). Several lines of evidence suggest that diabetes in the NOD mouse is an autoimmune disease mediated by T cells: First, Thy-1,2+ cells predominate in the cellular islet infiltration (3); second, neonatal thymectomy prevents the disease (4) ; third, NOD nu/nu mice do not develop diabetes (5).Further identification of immune cells involved in the destruction of insulinproducing cells has been hindered by lack of suitable in vivo transfer models . The NOD mouse has a particular MHC haplotype due to unique I-A specificity (6) that prevents the inoculation of NOD lymphoid cells into MHC-compatible strains. Attempts to derive lines of nondiabetic mice from the original NOD nucleus have also been unsuccessful . Recently, it has been shown (7) that the transfer of spleen cells from diabetic mice into diabetes-prone NOD adults greatly promoted the onset of overt diabetes, provided that the recipients had been sublethally irradiated. In addition, adoptive transfer required recipients older than 6-8 wk who, presumably, had already begun to self-damage their pancreatic islets as inferred from histological studies (2). This latter condition limits the validity of the model to account for the whole history of ß cell destruction, particularly in its initial stages .In this study we show that diabetes can be adoptively transferred to NOD neonates by spleen cells from diabetic NOD donors . Overt diabetes, which is correlated with >90% of ß cell destruction (8, 9) occurred as early as 21 d of age, at a time when pancreases of noninjected mice were still free of histological changes. The susceptibility of the recipients to the transfer was limited in time and declined after 3 wk of age. We also show that the neonatal model of transfer A. Bendelac was supported by a fellowship from the Foundation pour la Recherche Médicale. This work was supported by funds from INSERM and Centre National de la Recherche Scientifique. J. Exp. MED.

An immunoregulatory role has recently been attributed to the discrete subset of major histocompatibility complex class I-restricted NK1+ mature heat-stable antigen- (HSA-) thymocytes expressing an unusual Vbeta8-biased T cell receptor repertoire. NK1+ T cells are the main interleukin (IL)-4 producers upon priming. We have studied the size and the function of this subset in the nonobese diabetic (NOD) mouse, a model of spontaneous T cell-mediated autoimmune insulin-dependent diabetes. This study was complicated by the absence in this strain of the NK1.1 allele, the only one for which an antibody is available. To circumvent this difficulty, the cells, hereafter designated the NK1+-like T subset, were characterized by the use of monoclonal antibodies which showed the Vbeta8 bias in the CD44+ Ly-49+ MEL-14- 3G11- thymocyte subset of non-autoimmune strains and of its absence in class I-deficient (beta2-microglobulin-/-) mice. A clear deficit in the number of NK1+-like cells was evidenced at 3 weeks of age in NOD mice. It was still present at 8 weeks of age in the double-negative CD4-CD8- population. The functional anomaly was even more striking: NOD mouse NK1+-like thymocytes virtually lacked the ability to produce IL-4 at 3 weeks and still showed a very reduced capacity at 8 weeks. NK1+ T cell deficiency was also suggested in the periphery by the reduction of Ly-49A+ cells in the spleen of 3- and 8-week-old NOD mice and the absence of short-term production of IL-4 in vitro by NOD mouse spleen cells 90 min after the administration of anti-CD3 antibody, a response attributed to NK1+ T cells. Taken together, these data demonstrate a very early defect in NK1+-like T cells which could be involved in the genesis of autoimmunity in NOD mice through a deficiency in Th2 cell function.