title: Cytotoxic T lymphocytes generated across and I-Ab mutant difference are directed against a molecule bearing Ia antigens.
abstract: The recently discovered B6.C-H-2bm12 (bm12) histocompatibility mutant bears a mutation of the I-A subregion of the H-2b haplotype. We have studied cytotoxic T lymphocytes (CTL) generated in secondary mixed lymphocyte culture (MLC) between the bm12 mutant and the strain of origin C57BL/6 (B6). In both directions, strong CTL responses were generated against lipopolysaccharide-stimulated, but not against concanavalin A-stimulated target cells. Studies of the specificity of the bm12 anti-B6 CTL response, using target cells from a panel of H-2 recombinants, showed that the CTL were directed against specificities of the I-Ab subregion. This conclusion was confirmed by the observation that the bm12 anti-B6 CTL could be specifically blocked by anti-Iab, but not by anti-Kb antisera. EL4 tumor cells, which express Kb and Db but not Iab antigens, were not lysed by the CTL. The combined data confirm that bm12 is an I-A subregion mutant and indicate that the I-A subregion antigens, recognized by antibody and those recognized by CTL, are probably present on the same molecules. The CTL effector cells generated in secondary MLC across the I-Ab mutant difference had the surface phenotype Lyt 1- 2+.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D007518:Isoantibodies; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D051379:Mice; D009154:Mutation; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D000939:Epitopes; D000949:Histocompatibility Antigens Class II; D007518:Isoantibodies; C029805:Lyt antibodies