Analysis of the (H-2b X H-2k)F1-restricted response to insulin. Ab alpha Ak beta hybrid Ia molecules restrict the response towards the glutamic acid A4 epitope.
The aim of these studies was to characterize the (H-2b X H-2k)F1-unique restriction element(s) responsible for presentation of bovine insulin (BI) to a long-term cultured T-cell line (BK-BI-1.2). (B10.BR X bm12)F1 spleen cells, which express a normal Ab alpha Ak beta molecule but a mutated Ak alpha Abm12 beta product on their cell surface, were perfectly able to act as BI-presenting cells. Antibody inhibition experiments with antibodies directed at I-Ak products revealed that monoclonal antibody 10-2.16, which reacts with the Ak beta polypeptide chain, abrogated BI-directed T-cell proliferation, whereas antibody H116-32.R5 with specificity for the Ak alpha chain was not inhibitory. These results identified the Ab alpha Ak beta complex as restriction structure. Recognition of BI in the context of the Ab alpha Ak beta molecule depended on the glutamic acid residue in position 4 of the A chain of bovine insulin. Twenty to twenty-five percent of the secondary proliferative response of (B10 X B10.BR)F1 lymph node T cells primed with BI in vivo was directed at the A4 determinant, suggesting that BK-BI-1.2 T blasts are representative of T-cell clones with measurable frequency. In (B10.BR X bm12)F1 mice, which lack a functional Ab alpha Ab beta restriction element, up to 80% of the proliferative response was dependent on the A4 epitope.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000939:Epitopes; D005971:Glutamates / Q000276:immunology; D018698:Glutamic Acid; D006579:Heterozygote; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D007328:Insulin / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D005971:Glutamates; D000949:Histocompatibility Antigens Class II; D007328:Insulin; D018698:Glutamic Acid