Varicella zoster virus-specific cytotoxicity following secondary immunization with live or killed vaccine

Subjects > or = 55 years of age were immunized with attenuated varicella zoster virus (VZV) vaccine (live) or with the same vaccine, which had been heated to 56 degrees C for 7 days (killed). The ability of subjects' blood lymphocytes to lyse target cells infected with VZV was determined before and 3 months after immunization using autologous Epstein-Barr virus (EBV) lymphoblasts as targets for human leukocyte antigen (HLA) class I restricted cytotoxicity and human fibroblasts as targets for unrestricted (natural killer [NK]) cytotoxicity. The live vaccine recipients showed an increase in their class I-restricted lysis of targets compared with the recipients of the killed vaccine. The two populations showed equivalent increase in their NK-dependent lysis of fibroblast targets. The results support the view that both the live and killed vaccines stimulate cytotoxicity by VZV-specific lymphocytes but that the live vaccine stimulates relatively more class I-restricted killing.