T-cell receptor V beta 5 usage defines reactivity to a human T-cell receptor monoclonal antibody

The monoclonal antibody 3D6 reacts with the T-cell receptor (Tcr) on the T-leukemic line HPBALL and with 2-13% of human peripheral blood T lymphocytes. In this study V alpha and V beta expression in a panel of T-cell populations and clones expressing the 3D6 epitope was determined by Southern and northern hybridization analysis. The results demonstrate that these 3D6-positive T cells, regardless of CD4/CD8 phenotype or function, express a gene of the V beta 5 family, also expressed by HPBALL. No correlation was found between 3D6 reactivity and expression of the HPBALL V alpha gene. The results demonstrate that 3D6 recognizes an epitope solely on the Tcr beta chain and that the use of this beta chain, together with an appropriate V alpha, can impart a diverse pattern of reactivity to a T cell.