title: Regulatory mechanisms in cell-mediated immune responses. VII. Presence of I-C subregion determinants on mixed leukocyte reaction suppressor factor.
abstract: The presence of H-2 gene products on mixed leukocyte reaction (MLR) supressor factor was investigated by passage of MLR-suppressor factor (SF) over solid immunoadsorbents prepared with various anti-H-2 subregion sera. Antisera with specificity for all or certain I subregion determinants removed or significantly reduced suppressor activity; adsorption was not consistent with K or D region specificity. The single I subregion specificity common to all adsorbing preparations was I-C. Serologic differentiation of I-C products of k and d haplotypes expressed on MLR-SF was established with antisera prepared in I-Cd/I-Ck disparate strain combinations. These sera define allelic T cell restricted Lad determinants encoded by I-C genes. MLR-SF prepared from (BALB/c X CBA)F1 mice and exposed to the I-Cd and I-Ck specific adsorbents demonstrated d and k haplotype specific adsorption respectively. F1 suppressor activity adsorbed on an anti-I-Cd column was eluted by glycine-HCl buffer and suppressed only BALB/c (H-2d) responses. B10.A suppressor activity was removed by anti-I-Cd sera, but was unaffected by anti-I-Ck sera, indicating that B10.A suppressor activity is encoded by an I-C subregion derived from the d haplotype. Antisera with anti-I-Jk specificity did not remove suppressor activity of various H-2k factors. Finally, adsorption with antisera directed against H-2-associated determinants of the allogeneic cell used to stimulate suppressor factor generation demonstrated that sensitizing alloantigens are not components of MLR suppressor factor. Thus among the major histocompatibility complex (MHC)-controlled suppressor factors, MLR suppressor factor is uniquely determined by the I-C subregion.
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D000939:Epitopes; D005796:Genes; D006183:H-2 Antigens / Q000235:genetics*; D007111:Immunity, Cellular; D007165:Immunosuppression Therapy; D007959:Lymphocyte Culture Test, Mixed; D008285:Major Histocompatibility Complex; D051379:Mice; D008815:Mice, Inbred Strains
chemical_list: D000939:Epitopes; D006183:H-2 Antigens