Specificity of γδ Receptor-Bearing Cytotoxic T Lymphocytes Isolated from Human Peripheral Blood

T-cell receptor (TcR)-gamma delta-bearing lymphocytes were isolated from the peripheral blood of two healthy donors by immunomagnetic separation and subsequently cultured. The cell lines generated showed two distinct patterns of cytotoxicity. One TcR-gamma delta + cell line (HG.D) lysed K562 and U937 target cells, three TcR-gamma delta + cell lines lysed Daudi cells, and one TcR-gamma delta + cell line showed a shift from the former to the latter specificity during culture. Cold target inhibition experiments showed that the HG.D effector cells which were cytotoxic against U937 cells also lysed K562 cells. The cytotoxicity against Daudi cells was strongly inhibited by monoclonal antibodies (MoAb) against the CD3 complex, whereas the cytotoxicity of the HG.D cell line against K562 and U937 was unaffected by such antibodies. The cytotoxicity against Daudi cells was also strongly inhibited in the presence of anti-TcR-gamma delta MoAb. However, in two of the Daudi-specific cell lines, strong cytotoxicity against K562 cells was induced by anti-TcR-gamma delta MoAb. Anti-LFA-1 MoAb caused only a partial inhibition of cytotoxicity, while anti-CD2 and anti-TcR-alpha beta MoAb were found to have no effect. The results indicate that human gamma delta receptor-bearing T cells demonstrate a certain degree of target cell specificity, and that recognition of some target cells may be mediated through the TcR-gamma delta.