Passive transfer of monoclonal antibodies specific for herpes simplex virus type 1 (HSV-1) glycoproteins gC or gD resulted in the generation of highly potent HSV-specific and H-2-restricted primary cytotoxic T-lymphocytes (CTL) in the lymph nodes of recipients provided they were injected at 12 h post-infection. When the same antibody was injected at 3 h before HSV infection, the recipients failed to generate primary anti-HSV CTL. Rather, lymph node cells from such donors proved unsuitable for the initiation in vitro of a secondary anti-HSV CTL response by restimulation.