The Journal of Immunology, Vol 143, Issue 2 446-451, Copyright © 1989 by American Association of Immunologists

ARTICLES

Arsonate-specific murine T cell clones. V. Antigen presentation by L cells transfected with normal and mutant class II genes

FL Norton, CB Davis, PP Jones and JW Goodman
Department of Microbiology and Immunology, University of California, San Francisco 94143.

Class II-restricted murine T cell clones specific for the immunogenic determinant L-tyrosine-p-azobenzenearsonate failed to proliferate to Ag presented by L cell lines transfected with and expressing the appropriate class II genes, but are activated to kill the APC in an Ag- dependent, MHC-restricted manner. Inhibition of APC proliferation was used as an assay to determine the relative contributions of polymorphic sites on the class II alpha- and beta-chains to MHC-restricted activation of I-A beta k-restricted cloned T cells. Transfectants expressing A beta k in conjunction with the alpha chain of k, u, or d were equally effective APCs, whereas transfectants expressing A beta u were completely ineffective, implicating the beta-chain as more critical for the presentation of L-tyrosine-p-azobenzenearsonate. Site- directed mutagenesis of polymorphic positions in the beta chain revealed a remarkable stringency for the k haplotype, in contrast to the relaxed alpha-chain requirement. These results, in conjunction with others, indicate that the relative contribution of polymorphic sites on class II alpha- and beta-chains to T cell Ag recognition can differ markedly, and, furthermore, may vary as a function of the Ag.