Recognition of superantigens by T cells predominantly involves the TCR
V beta region. The contribution of reactivity from the non-V beta por
tion of the TCR remains less clear. We have investigated the V-alpha r
epertoire of T cells bearing one V(b)eta element responding to differe
nt superantigen or polyclonal stimuli. The data indicate that the V-al
pha chain is not directly involved in superantigen recognition, since
unrelated superantigens do not stimulate cells bearing different V-alp
ha elements. Instead, analysis of V-alpha elements used preferentially
in the CD4(+) or CD8(+) cells, shows that the V-alpha-regions predomi
nating in the superantigen response are the same V(alpha)s that are po
sitively selected into the CD4(+) lineage. Thus the ability of a V-alp
ha-region to either aid or hinder the interaction with class II predic
ts its frequency in a superantigen-responding population of T cells.