FIGURE 2

gzmB⁺CTLs induce cell death independently of Bid, Bak, Bax and caspase activity. Gp33-pulsed MEF.wt, MEF.Bid^-/- and MEF.Bak Bax^-/- (a) or MEF.wt, MEF.Casp 3 7^-/- and MEF.Casp 9^-/- and (b) cells were incubated with ex vivo virus-immune gzmB⁺CTL (4 h, 10:1 effector/target ratio) in the presence or absence of the general caspase inhibitor Ac-ZVAD-fmk (80 M) or the caspase-3/-7 inhibitor Ac-DEVD-fmk (not shown) (a, 80 M both). Target cell death was monitored by survival assay as described in Materials and Methods. Data are given as meanS.E.M. of five (MEF.wt, MEF.Bid^-/-; a), four (MEF.Bak Bax^-/-; a) and three (MEF.wt, MEF.Casp 3 7^-/-, MEF.Casp 9^-/-, b) independent experiments, respectively. (c) Gp33-pulsed MEF.wt and MEF.Bak Bax^-/- cells were incubated with ex vivo virus-immune gzmB⁺CTL at different effector/target ratio (4 h) in the presence or absence of the general caspase inhibitor Ac-ZVAD-fmk (80 M). Target cell death was monitored by survival assay as described in Materials and Methods. Representative of two independent experiments. Ctr: only target cells; ctr ZVAD: target cells+ZVAD-fmk