title: In vitro analysis of allogeneic lymphocyte interaction. II. I-region control of the activity of a B-cell-derived H-2-restricted allogeneic effect factor and its receptor during B-cell activation.
abstract: A genetically restricted allogeneic effect factor (AEF) derived from a mixed lymphocyte culture reaction between Ia-negative activated responder cells and irradiated T-cell-depleted stimulator cells was characterized. Restricted AEF is a B-cell-derived soluble helper factor which consists in part of Ia antigens controlled by the I-A subregion of the stimulator haplotype; additional control by the I-B, I-E, and I-C subregions, although unlikely, could not be excluded. This factor helps B cells of only its own haplotype or of haplotypes which carry an I-A and/or I-B subregion identity. Unprimed as well as hapten-primed Ia-positive B cells express a receptor for restricted AEF. The results indicate that the B-cell receptor for AEF is determined by the I-A subregion. Both restricted AEF and its receptor may therefore be products of the same I-region gene(s). The data are compatible with the hypothesis that the AEF Ia antigens serve as a second signal required for B-cell activation to IgG antibody production.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology*; D001665:Binding Sites; D005802:Genes, MHC Class II; D006183:H-2 Antigens / Q000235:genetics*; D007519:Isoantigens; D008198:Lymph Nodes / Q000276:immunology; D008211:Lymphocyte Cooperation; D051379:Mice; D012995:Solubility; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology
chemical_list: D006183:H-2 Antigens; D007519:Isoantigens