Abstract
Previous reports of TCR V.beta. usage, studying either expression of a single V.beta. in a wide panel of strains (6, 7, 10, 12, 13), or expression of multiple V.beta.s in a very limited strain distribution (14,15), have identified instances of clonal deletion of potentially autoreactive T cells specific for either self E.alpha.E.beta. or minor lymphocyte stimulatory (Mls) antigens. The present study has investigated the range of self antigens that can influence V.beta. usage by evaluating expression of 16 V.beta. families in 30 strains of mice. It was found that significant decreases in expression occur in at least 8 of the 16 V.beta. families and that dominant influences on the T cell v.beta. repertoire are exerted by expression of Mlsa, Mlsc, and MHC gene products. Decreased expressions of V.beta.5, -11, -12, and -16 were influenced by MHC gene products. The patterns of decreased expression seen in intra-MHC recombinant strains and strains of different non-MHC background were distinct for V.beta.11, -12, and -16, suggesting that different ligands are involved in the deletion of T cells expressing each of these V.beta. genes. Mice expressing Mlsa show decreased expression of V.beta.9 as well as V.beta.9 as well as V.beta.6. Mlsc mice lacked V.beta.3 expression in those strains where the expressed MHC type was compatible with a strongly stimulatory Mlsc phenotype. V.beta.7 was strongly influenced by both MHC and non-MHC products that are not yet identified. These results demonstrate that strain-specific decreases of mRNA expression occur in a major portion of the TCR repertorire. Self antigens including Mlsa, Mlsc, and E.alpha.E.beta., as well as additional MHC and non-MHC products, appear to induce these decreases in expression in the process of eliminating self-reactive T cells from the mature T cell pool.