CO-STIMULATION WITH LFA-1 TRIGGERS APOPTOSIS IN GAMMA-DELTA T-CELLS ON T-CELL RECEPTOR ENGAGEMENT

Stimulation of T cells through the T cell receptor (TcR) initiate acti vation pathways, and paradoxically can also result in activation-induc ed cell death. Many factors influence a stimulated cell's decision to manifest one or the other. Here we show that co-stimulation with LFA-1 plays a key role in the choice between the two fates, differentiating between alpha beta and gamma delta T cells. Peripheral gamma delta T cells but not alpha beta T cells undergo apoptosis upon co-cross-linki ng of TcR and LFA-1 in MRL lpr/lpr mice as well as +/+ mice. Our resul ts suggest that apoptosis of gamma delta T cells is inducible by combi ned stimuli independent of the Fas-mediated pathway.