MECHANISMS OF SIMIAN GAMMA-DELTA T-CELL CYTOTOXICITY AGAINST TUMOR AND IMMUNODEFICIENCY VIRUS-INFECTED CELLS

The mechanisms of cytotoxic killing of various tumor cell lines and im munodeficiency virus-infected T cell lines by simian gamma delta T cel ls were examined. The lysis of the majority of the target cell lines b y gamma delta effecters was calcium-dependent, indicating that cytotox icity is mediated by the perforin/granzyme pathway rather than the Fas -FasL pathway, with the exception of Jurkat cells. The gamma delta T c ells were able to suppress SIV replication as measured by the p27 ELIS A and the suppression was contact-dependent. We further determined tha t the target cells were induced to undergo apoptosis by the gamma delt a T cell effecters. These results contribute to our understanding of t he function of simian gamma delta T cells and their similarities to hu man gamma delta T cells, and extend our knowledge on the cytotoxic mec hanisms employed by gamma delta T cells in general.