T-CELL RECEPTOR V-ALPHA-V-BETA COMBINATORIAL SELECTION IN THE EXPRESSED T-CELL REPERTOIRE

This study has evaluated whether preferential pairing occurs between TCR alpha- and beta-chains expressing specific Valpha and Vbeta gene products in the mature peripheral T cell population, as a result of either thymic selection or of structural constraints on chain pairing. The association of specific Valpha products with specific Vbeta products on individual T cells was found, in multiple instances, to be highly selective. Moreover, patterns of preferential Valpha-Vbeta association were highly strain-specific and were independently expressed in CD4+ and CD8+ T cell subsets. Although these findings do not exclude the possibility that structural constraints may limit Valpha-Vbeta pairing in other instances, they indicate that the observed instances of skewed expression are not caused by structural constraints in chain pairing. Rather, they suggest that strain-specific selective events alter the expressed ValphaVbeta repertoire as a result of recognition of self or environmental Ag during T cell repertoire selection.