title: Antigen presenting function of class II MHC expressing pancreatic beta cells.
abstract: Class II major histocompatibility complex (MHC) gene expression in the mouse is generally limited to thymic epithelium and bone marrow-derived cells such as B lymphocytes and cells of the macrophage/dendritic cell lineage (M phi/DC). Class II-bearing B lymphocytes and M phi/DC possess antigen presenting cell (APC) function; that is, they can stimulate T lymphocytes reactive to either antigen plus MHC or foreign MHC alone. To assess whether non-bone-marrow-derived cells can acquire APC function and elicit graft rejection through expression of class II, we studied transgenic pancreatic islet beta cells that express a foreign class II (I-E) molecule. In vivo, grafts of I-E+ transgenic islets into I-E- naive hosts are not rejected unless the host is primed by an injection of I-E+ spleen cells. In vitro, the I-E+ beta cells are unable to stimulate T lymphocytes reactive to I-E plus a peptide antigen. Paradoxically, they induce antigen specific unresponsiveness in the T cells. We propose that expression of class II on non-lymphoid cells may serve as an extrathymic mechanism for maintaining self tolerance.
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006084:Graft Rejection; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D007108:Immune Tolerance; D007328:Insulin / Q000096:biosynthesis; D007515:Islets of Langerhans / Q000196:embryology / Q000276:immunology*; D016381:Islets of Langerhans Transplantation; D008213:Lymphocyte Activation; D051379:Mice; D008822:Mice, Transgenic; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II; D007328:Insulin