title: Immune response to the p-azobenzenearsonate (ABA)-GAT conjugate: role of I region genes in the selective activation of ABA-specific or GAT-specific T helper cells.
abstract: Immunization of GAT non-responders with ABA-GAT leads to the activation of ABA-specific T cells. These hapten specific T cells are Lyt-1+2- helper cells capable of inducing anti-ABA antibody responses in vivo or B cell activation in vitro. However, their activation does not modify the GAT non-responder phenotype. Immunization of GAT responder mice with ABA-GAT activates GAT-specific T cells, which can help anti-ABA and anti-GAT antibody responses. Since the responder and non-responder strains used in these experiments differ only in the alleles present in the I region, the results suggest that the selective activation of hapten- or carrier-specific T cells is controlled by I region genes. Yet sensitization of the two strains with ABA-KLH or ABA-Tyr induces KLH-specific or ABA-specific T cells, respectively. This provides further evidence that the use of an immunogenic carrier prevents the expression of the hapten-specific T cell clones present in the repertoire of both responder and non-responder animals. Macrophages from responder animals pulsed with ABA-GAT can present ABA and GAT determinants to T cells. Thus, the absence of ABA-specific T cells in responders primed with ABA-GAT and their presence in GAT non-responders reflects a competition between hapten- and carrier-specific T cells and not an epitope selection by macrophages. We discuss the significance of the results in terms of Ir genes determining the self-plus-antigen-specific T cell repertoire rather than controlling antigen presentation by macrophages.
mesh_terms: D000818:Animals; D001391:Azo Compounds / Q000276:immunology*; D000939:Epitopes; D005260:Female; D005802:Genes, MHC Class II; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000276:immunology*; D011108:Polymers; D013601:T-Lymphocytes / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D010132:p-Azobenzenearsonate / Q000276:immunology*
chemical_list: D001391:Azo Compounds; D000939:Epitopes; D010455:Peptides; D011108:Polymers; C020749:GAT; D010132:p-Azobenzenearsonate