CD8⁺ and CD4⁺ polyclonal EBV-specific CTL express CD16/γ after transduction and mediate ADCC. EBV-specific CTLs were selected against the autologous BLCL and transduced with retroviral pMX-CD16/FcϵRIγ according to the protocol described in “Materials and methods.” Note in panel A that a few CD16⁺CD3– cells (NK cells) were present among the CTL. After transduction 14% of the CTL expressed CD16, at a level comparable to that observed in NK cells still present in the culture (B). After immunoselection and restimulation, CTLs were stained with CD16-PE and CD4-FITC or CD8-FITC to analyze the proportion of transduced CD4 and CD8, respectively (C). Finally, a panel of CD4⁺ and CD8⁺ T-cell clones was derived from the CTL to precisely assess the effect of CD16/γ transduction on the cytolytic potential of CD4 and CD8 CTLs against autologous BLCL. In panel D, examples show the dramatic increase in cytolytic scores observed for both the CD4⁺ and CD8⁺ clones when tested against the autologous BLCL in the presence of anti-CD20 (effector-to-target ratio = 30:1). Note the example of clone CD8 no.1, which was probably not EBV specific but became an effector in the presence of mAb.