title: Monoclonal antibodies defining serologically distinct HLA-D/DR related Ia-like antigens in man.
abstract: Four monoclonal antisera-identifying antigens with the identical tissue distribution and molecular weight of previously described Ia-like antigens were characterized. Two of these antisera, I-1 and I-2, identified antigens expressed on the HLA-D/DR positive cells from all HLA heterozygous individuals. Further characterization on homozygous typing cells (HTC's) demonstrated that I-2 was not reactive with most Dw7 and Dw11 HTC's. Monoclonal antisera, termed I-LR1 and I-LR2, defined polymorphic Ia-like antigens that demonstrated restricted expression on cells from HLA heterozygous individuals. Antigen I-LR1 was expressed on cells from 60% of HLA heterozygotes and its reactivity with HTC's did not conform to any previously described monotypic or supertypic HLA-D/DR pattern. In contrast, I-LR2 was expressed on 40% of HLA heterozygotes and identified only HLA-DR3, 5 and 6 HTC's. Studies of families with HLA recombinants permitted the demonstration that the I-LR1 and I-LR2 antigens are tightly linked to the HLA-D/DR locus. These experiments permit the direct demonstration by immunoprecipitation, linkage studies, and MHC recombinant families that the p29,34 complex in man is closely linked to or is within the HLA-D/DR locus. These studies suggest that the human Ia-like antigens are more heterogeneous than previously demonstrated and that monoclonal antisera will be useful in further defining the structural, genetic, and functional characteristics of these molecules.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D008040:Genetic Linkage; D006579:Heterozygote; D000949:Histocompatibility Antigens Class II; D006720:Homozygote; D006801:Humans; D006822:Hybrid Cells / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D011995:Recombination, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II