Activated human NK and CD8+ T cells express both TNF-related apoptosis inducing ligand (TRAIL) and TRAIL receptors, but are resistant to TRAIL-mediated cytotoxicity.

The expression of TRAIL and TRAIL receptors was investigated in resting and cytokine-activated purified primary human NK and CD8(+) T cells. We found out that once activated the major cytotoxic effector cells are potentially sensitive to TRAIL but are physiologically protected from its apoptotic action by intracellular level of c-FLIP.