Figure 2.

Inhibitors of Fas-dependent CTL activity prevent cytolysis by LCMV-specific CD4⁺ CTLs. Effector cells were prepared from β₂m⁻ mice at 10 days after i.p. infection and tested for their ability to lyse ⁵¹Cr-labeled LB27.4 cells. (A) Effector cells were preincubated in medium only (•, ○) or with 5 μM emetine (▵) and tested for their ability to lyse either infected target cells (▵, •) or noninfected target cells (○). (B) In separate experiments effector cells were assayed for their ability to lyse LCMV-infected target cells in the presence (hatched bars) or absence (solid bars) of 7 μg of Fas-Ig. Lysis of noninfected targets in the absence of Fas-Ig is also shown (open bars). Addition of 7 μg of human IgG1 does not inhibit CTL activity (data not shown).