Amplification of natural killer activity of mouse lymphocytes by vincristine

The possible influence of Vincristine (VCR) on NK-mediated cytolysis has been studied pretreating effector (E) or target (T) cells with the drug or adding the agent to E + T mixture during the 18-hour assay. Substantial increase of cytotoxicity was found when VCR was added to E + T cells, but not when effector or target cells were pretreated with the drug. This phenomenon was confirmed with effector splenocytes of various strains of mice, including athymic nude donors deprived of plastic-adherent or nylon-wool adherent accessory cells. Moreover, the agent did not produce irreversible inactivation of the suppression activity of splenocytes collected from DBA/2 donors infected with Friend leukaemia virus.