Daudi lymphoma killing triggers the programmed death of cytotoxic Vγ9/Vδ2 T lymphocytes

A common feature of human Vγ9/Vδ2 γδ T lymphocytes is their ability to kill Daudi lymphoma cells. We show here that during this killing a substantial fraction of cytotoxic γδ T cells dies as well. Their death has morphologic, cytometric, and biochemical features of apoptosis and depends on TCR triggering. We suggest that interaction with the target physiologically induces the programmed death of the cytotoxic γδ effector. The death of activated γδ T cells upon challenge with the relevant Ag may represent a negative feedback mechanism and contribute to explain the limited time span of γδ T cell expansions during infectious diseases, even when pathogens are not eliminated and persist in the host.