Functional similarities of A_eE_α Ia molecules as determined by analysis with T-cell clones

Recognition of A_eE_α Ia antigens at the functional level was investigated using T-cell clones. The reactivities of an alloreactive and an antigen-reactive clone, both of which recognized A_eE_α Ia molecules, were compared on a panel of stimulator/antigen-presenting cells of various genotypes. The two clones recognized all tested A_e^bE_α^xIa molecules, where x is a haplotype capable of expressing an Ia.7-bearing E_α polypeptide. Ia antigen recognition by either clone could be inhibited by the monoclonal antibody Y-17, which recognizes a combinatorial serologic determinant on certain A_eE_α molecules. There were no differences in the recognition of Ia by the alloreactive versus the antigen-reactive clone, suggesting that Ia antigens are recognized by the two clones in a fundamentally similar way. The recognition of these various Ia molecules by the two cloned T-cell lines provides evidence that the E_α polypeptides from H-2 haplotypes k, d, r, and u are functionally indistinguishable.