Analysis of the (H‐2 b × H‐2 k )F 1 Restricted Response to Insulin

The aim of these studies was to characterize the (H‐2 b × H‐2 k )F 1 ‐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 × bm12)F 1 spleen cells, which express a normal A b α A k β molecule but a mutated A k α AA bm12 β product on their cell surface, were perfectly able to act as BI‐presenting cells. Antibody inhibition experiments with antibodies directed at I‐A k products revealed that monoclonal antibody 10–2.16, which reacts with the A k β polypeptide chain, abrogated BI‐directed T‐cell proliferation, whereas antibody H116–32.R5 with specificity for the A k α chain was not inhibitory. These results identified the A b α A k β complex as restriction structure. Recognition of BI in the context of the A b α A k β 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 × B10.BR)F 1 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 × bm12)F 1 mice, which lack a functional A b α A b β restriction element, up to 80% of the proliferative response was dependent on the A4 epitope.