title: Cytotoxic T lymphocyte responses in allogeneic radiation bone marrow chimeras. The chimeric host strictly dictates the self-repertoire of Ia-restricted T cells but not H-2K/D-restricted T cells.
abstract: The present report has used fully H-2 allogeneic radiation bone marrow chimeras to assess the role of host restriction elements in determining the self-specificity of Ia- and H-2K/D-restricted T cells that participate in the generation of trinitrophenyl (TNP)-specific cytotoxic T lymphocytes (CTL). It was demonstrated that there exists a stringent requirement for the recognition of host thymic-type Ia determinants, but there exists only a preference for host thymic-type H-2K/D determinants. Indeed, once the stringent requirement for recognition of host Ia determinants was fulfilled, anti-TNP CTL were generated in response to TNP-modified stimulators that expressed either donor-type or host-type H-2K/D determinants. The CTL that were generated in response to TNP-modified donor-type stimulators were shown to be specific for TNP and restricted to the non-thymic H-2K/D determinants of the chimeric donor. Thus, these results demonstrate in a single immune response that the thymic hypothesis accurately predicts the self-specificity expressed by Ia-restricted T cells, but does not fully account for the self-specificity expressed by H-2K/D-restricted T cells. These results are consistent with the concept that H-2K/D-restricted T cells, but not Ia-restricted T cells, can differentiate into functional competence either intrathymically or extra-thymically. The present results are also informative for understanding the cellular interactions that are required for the generation of antigen-specific CTL responses. The Ia-restricted T cells that are required for the generation of H-2K/D-restricted anti-TNP CTL were shown to be helper T (TH) cells since (a) like TH cells functioning in antibody responses, they were specific for Ia determinants expressed by accessory cells, and (b) their function could be replaced by either TNP-primed, irradiated TH cells or by nonspecific soluble helper factors. It was also shown that the T-T cell interaction between Ia-restricted TH cells and H-2K/D-restricted precursor CTL (pCTL) is not Ia restricted. Rather, the results demonstrate that the generation of anti-TNP CTL responses involve two parallel sets of major histocompatibility complex-restricted cell interactions, an Ia-restricted TH-accessory cell interaction required for TH cell activation, and an H-2K/D-restricted pCTL-stimulator cell interaction required for pCTL stimulation. The interaction between activated TH cells and stimulated pCTL is mediated, at least in part, by nonspecific soluble helper factors.
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D003208:Concanavalin A / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D005802:Genes, MHC Class II; D006183:H-2 Antigens / Q000235:genetics*; D008222:Lymphokines; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D011828:Radiation Chimera; D013154:Spleen / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D006183:H-2 Antigens; D008222:Lymphokines; D014301:Trinitrobenzenes; C021649:concanavalin A-induced helper factors; D003208:Concanavalin A