Lysis of recombinant HIV-vaccinia–infected BLCL by CTL clones and a T-cell line is inhibited by calcium chelation, but not by fas-blocking antibody. Autologous BLCL targets were infected overnight with HIV env (A) or gag (B) expressing-vaccinia or with control lacZ-vaccinia (□) and labeled with ⁵¹Cr. HIV-expressing target cells were pretreated with medium (◊), EGTA-MgCl₂(▵) or fas blocking antibody (○) before adding either the env-specific clone 352-env52 (A) or the gag-specific clone 352-gag27 (B). (C) The nef-specific clone 352-nef26 and the RT-specific clone 307-BR21 were tested similarly at an E:T ratio of 5:1 against control vaccinia-infected targets (□) or HIV-vaccinia (nef or RT) infected targets in the presence of medium (▪), fas-blocking antibody (▧) or EGTA (▨). (D) Cytotoxicity by a PHA-stimulated bulk T-cell line from subject 352 was tested against autologous BLCL targets infected overnight with HIV-expressing vaccinia or with control lacZ-vaccinia. Target cells were pretreated with medium (▪) or fas-blocking antibody (▧) for use in a 6-hour cytotoxicity assay at an E:T ratio of 25:1.