Analysis of T cell antigen receptor (TCR) expression by human peripheral blood CD48 αβT cells demonstrates preferential use of several Vβ genes and an invariant TCR α Chain

CD4 CD8 (double negative [ON]) α/β T cells are a largely uncharacterized subpopulation of unknown function. To investigate whether these cells are selected to recognize particular antigens or antigen-presenting molecules, ON α/β T cells were purified from the peripheral blood of five normal donors and their T cell receptor (TCR) a and fi chains were examined. Random cloning of TCR a chains by single-sided polymerase chain reaction (PCR) amplification identified an invariant rearrangement between Va24 and JaQ, with no N region diversity, which was expressed preferentially by DN α/β T cells from all donors. Random cloning also identified a precise Va7.2-Ja(IGRJa14) rearrangement, with two variable amino acids encoded in the V-J junction, which was enriched in the ON α/β T cell preparations from some, but not all, donors. Analysis of TCR β chains by quantitative PCR. amplification demonstrated that the expression of four Vfl gene families, Vβ, 8, 11, and 13, was markedly increased in these ON α/β T cell preparations. The expression of particular TCRs by ON α/β T cells from multiple donors indicates that these cells, or at least a subpopulation of cells with this phenotype, recognize a limited spectrum of antigens and suggests that they may use nonpolymorphic antigen-presenting molecules.