Effect of TTP plasma and TTP-associated cytokines on c-FLIP expression in pulmonary versus dermal MVECs. Levels of c-FLIP, normalized to GAPDH, were assessed by Western blotting 18 hours after exposure of ECs to normal plasma (2% vol/vol), TTP plasma (2% vol/vol), or cytokines. (A) Basal levels of c-FLIP in HUVECs and dermal MVECs were equivalent, and significantly greater than basal FLIP levels in pulmonary MVECs (summary of 4 experiments; P = .007). TTP plasma suppressed basal FLIP expression only in dermal MVECs (5 different TTP plasmas tested; P = .007). (B) TTP plasma (P < .01) and the combination of TRAIL (2 ng/mL) plus IFN-γ (0.1 ng/mL; P < .01) suppressed FLIP expression in dermal MVECs, while either cytokine alone had no effect. Neither TTP nor cytokine combinations significantly affected basal FLIP levels in pulmonary MVECs. Standard deviations for all mean values are provided.