Antigen driven lymphocyte expansion is limited by cell death in peripheral lymphoid tissues avoiding overwhelming immune responses and autoimmunity. Signals associated with ligation of Fas can lead to lymphocyte apoptosis, but further, Fas-independent mechanisms have been postulated. Recent in vitro experiments demonstrated a role for tumor necrosis factor (TNF). In mice transgenic for the T cell receptor (TCR) specific for H-2Dand and the lymphocytic choriomeningitis virus (LCMV) glycoprotei...