CTL recognition of H-RS lines pretreated with recombinant human IL-10. (A) The biological activity of the human IL-10 was shown by its ability to inhibit IFN-γ production by PHA-treated PBMCs. However, IL-10 pretreatment had no inhibitory effect on CTL-mediated lysis of H-RS lines or an LCL (B-D). (B) A B8-restricted EBNA 3A-specific CTL clone tested against HDLM2 infected with a vaccinia vector expressing EBNA 3A (vE3A) or infected with the vector alone (vTK−). (C) An A2-restricted LMP 2-specific CTL clone tested against L1236 expressing LMP 2 from a vaccinia vector (vLMP2) or the vector alone (vTK−). (D) An A11-restricted EBNA 3B-specific CTL clone tested against L540, KMH2, and an A11-matched LCL expressing EBNA 3B from a vaccinia vector (vE3B) or the vector alone (vTK−). E:T = 5:1 (▪) and 1:1 (▨). All results are expressed as % specific lysis + 1 SD and are representative of several repeated assays.