Recognition of H-RS lines and LCLs by CTL clones pretreated with recombinant human IL-10. (A) HDLM2 and a B8-positive LCL target were infected with a vaccinia vector expressing EBNA 3A (vE3A) or with the vector alone (vTK−) and then tested for recognition by a B8-restricted EBNA 3A-specific CTL clone AR64.64 pretreated with IL-10 at the concentrations shown. E:T = 5:1 (▪) and 2:1 (▨). (B) KMH2, L540, and an A11-positive LCL target were infected with a vaccinia vector expressing EBNA 3B (vE3B) or with the vector alone (vTK−) and then tested for recognition by an A11-restricted EBNA 3B-specific CTL clone CM14 pretreated with IL-10 at the concentrations shown. E:T = 4:1 (▪) and 1:1 (▨). All results are expressed as % specific lysis + 1 SD and are representative of several repeated assays.