CELL-RECEPTOR V-ALPHA-4 IS EXPRESSED BY A SUBPOPULATION OF V-BETA-6 T-CELLS THAT RESPOND TO THE BACTERIAL SUPERANTIGEN STAPHYLOCOCCAL-ENTEROTOXIN-B

A subpopulation of murine minor lymphocyte-stimulating locus Ag (Mls)- 1(a)-responsive, TCR V beta 6-expressing T hybrids was responsive to t he superantigenic bacterial toxin, staphylococcal enterotoxin B (SEE), presented by murine MHC class II molecules.,Comparative functional an d surface marker analyses showed that this heterogeneity was not cause d by nonspecific effects. It seemed, therefore, that the ability of th e TCR V beta 6 T hybrids to respond to SEE was regulated by non-V beta TCR elements. cDNA sequencing analyses of the TCR beta- and alpha-cha ins expressed by the V beta 6 T hybrids and a beta-chain cDNA gene tra nsfer experiment indicated that although J beta, CDR3 beta, J alpha, a nd CDR3 alpha were not the relevant elements, SEE responsiveness did c orrelate with the expression of two different members of the V alpha 4 family. A functional analysis of a separate panel of V alpha 4 T hybr ids expressing different V beta elements, including V beta 6, specific ally associated SEE responsiveness with the V alpha 4, V beta 6 combin ation. Overall, the data obtained with both panels of T hybrids showed SEE responsiveness in five out of five V beta 6, V alpha 4 T hybrids, and not in either 11 V beta 6 T hybrids expressing a variety of other V alpha elements or four V alpha 4 T hybrids expressing V beta 11 14, and 15 elements. Thus, our experiments show for the first time a spec ific, positive qualitative effect of a defined V alpha element on resp onsiveness to a bacterial superantigen. Finally, this study has identi fied four new V alpha elements.