The Vbeta8.3 TCR is a variant of the TCR beta chain. It is expressed by a subset of peripheral blood T cells and is increased in response to some viral infections and tumors. T cells expressing the alpha/beta T cell receptor use clonally distributed TCRs to recognize cell-bound antigens such as peptide/MHC complexes and viral superantigens. The alpha/beta TCR is an oligomeric TCR complex composed of covalently bound alpha and beta chains involved in antigen recognition and the non-covalently associated monomorphic proteins CD3delta, gamma, epsilon, and ? chains. The 8C1 antibody has been used for the identification of T cells expressing Vbeta8.3 by flow cytometry.