DAUDI LYMPHOMA KILLING TRIGGERS THE PROGRAMMED DEATH OF CYTOTOXIC V-GAMMA-9 V-DELTA-2 T-LYMPHOCYTES/

A common feature of human V gamma 9/V delta 2 gamma delta T lymphocyte s is their ability to kill Daudi lymphoma cells. We show here that dur ing this killing a substantial fraction of cytotoxic gamma delta T cel ls dies as well. Their death has morphologic, cytometric, and biochemi cal features of apoptosis and depends on TCR triggering. We suggest th at interaction with the target physiologically induces the programmed death of the cytotoxic gamma delta effector. The death of activated ga mma delta T cells upon challenge with the relevant Ag may represent a negative feedback mechanism and contribute to explain the limited time span of gamma delta T cell expansions during infectious diseases, eve n when pathogens are not eliminated and persist in the host.