title: Immune response to the p-azobenzenearsonate-L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) conjugate. III. Mechanisms of Ir gene-controlled phenotype conversion.
abstract: Immunization of GT (random copolymer of L-glutamic acid51-L-tyrosine49) nonresponder animals with p-azobenzenearsonate (ABA) GT conjugates elicits an antibody response to both ABA and GT epitopes which is induced by ABA-specific T helper cells. Expression of these hapten-specific helpers is under the control of an I region gene which also regulates the proliferative T cell response to ABA. Conversion of the unresponsive phenotype to GT is, therefore, dependent on the ABA Ir gene and escapes the influence of the GT-specific I region-controlled suppressive pathway. Studies on the influence of ABA/polymer coupling ratio on T and B cell responses suggest that ABA-specific T cells, like conventional carrier-specific helpers, require linked interactions with B lymphocytes to provide helper signals. GAT (terpolymer of L-glutamic acid60-L-alanine30-L-tyrosine10) nonresponder animals immunized with ABA-GAT conjugates also develop an antibody response to ABA which is induced by ABA-specific T helper cells. Comparison of antibody affinity, specificity, isotypes and idiotypes in different mouse strains demonstrates that hapten-specific helper cells stimulate antibody responses to ABA which are qualitatively similar to those induced by GAT-specific helpers. However, ABA-specific helper cells do not permit the conversion of the I region gene-controlled nonresponder phenotype to GAT. The data suggests that high ABA density, which is required for optimal ABA help expression, extinguishes the immunogenicity of GAT determinants at both T and B cell levels.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis*; D000915:Antibody Affinity; D000918:Antibody Specificity; D001391:Azo Compounds / Q000276:immunology*; D005785:Gene Conversion; D005802:Genes, MHC Class II; D006241:Haptens; D007126:Immunoglobulin Allotypes; D051379:Mice; D008815:Mice, Inbred Strains; D010455:Peptides / Q000276:immunology*; D010641:Phenotype; D011108:Polymers; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D010132:p-Azobenzenearsonate / Q000235:genetics / Q000276:immunology*
chemical_list: D000906:Antibodies; D001391:Azo Compounds; D006241:Haptens; D007126:Immunoglobulin Allotypes; D010455:Peptides; D011108:Polymers; C020749:GAT; D010132:p-Azobenzenearsonate