Tolerance of class I histocompatibility antigens expressed extrathymically.
Although convincing evidence has been obtained for the imposition of self-tolerance by the intrathymic deletion of self-reactive T cells, the development of tolerance to antigens which are expressed only in the periphery is not so well understood. We have approached this question by creating transgenic mice which carry a class I major histocompatibility complex (MHC) gene (H-2Kb) linked to the rat insulin promoter. Mice expressing the transgene develop diabetes, but do not appear to mount an immune response against the transgene-expressing pancreatic beta-cells, even when the transgene is allogeneic with respect to the endogenous host H-2 antigens. We have now explored the mechanism of this tolerance further. We find that spleen cells from pre-diabetic transgenic (RIP-Kb) mice do not kill targets bearing H-2Kb, whereas thymus cells from the same mice do. The unresponsiveness of these spleen cells can be reversed in vitro by providing recombinant interleukin-2 (rIL-2). In older, diabetic mice, responsiveness develops as the pancreatic beta-cells are lost. Our results point to an extrathymic mechanism of tolerance induction, dependent on the continuous presence of antigen and the lack of IL-2 in the local environment of potentially reactive T cells.
Morahan
G
G
Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Allison
J
J
Miller
J F
JF
D000818:Animals; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D007108:Immune Tolerance; D007376:Interleukin-2 / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology
D015395:Histocompatibility Antigens Class I; D007376:Interleukin-2