Cell-mediated cytotoxicity during vaccinia virus revaccination in man: influence of antibodies and interferon

Seven healthy human adults were revaccinated with vaccinia virus. Cell-mediated cytotoxicity to vaccinia virus-infected fibroblasts was investigated on the day of vaccination and on days with peak activity. Three donors were studied until day 30 after vaccination. The addition of interferon to cytotoxicity reactions resulted in an increase in killing. This increase was not seen when antibodies were added. When a mixture of lymphocytes from a revaccinated and a non-revaccinated donor was used as effector cells, the killing observed corresponded to the killing seen with lymphocytes from the revaccinated donor, when tested alone. This finding indicates that no antibodies or other soluble mediators capable of increasing cytotoxicity are released from the lymphocytes during the cytotoxicity assay.