Immunovac-VP-4, immunomodulator decreases immunosuppression and enhances the cytotoxic activity induced by the cytostatic Cisplatin

The influence of the vaccine Immunovac-VP-4, prepared from the antigens of opportunistic microorganisms, on the proliferative and cytotoxic activity on peripheral blood mononuclears (PBMN) from healthy donors in vitro and on spleen cells of CBA mice in vivo during their incubation with Cisplatin was studied. VP-4 produced a dose-dependent, stimulating effect on the proliferative potential of PBMN and, when used in the highest of all tested doses (20 microg/ml), increased the Cisplatin-suppressed proliferative activity of PBMN in 9.4-fold. VP-4 increased the cytotoxic activity of PBMN on tumor line cells K-562 (38,4 to 60.1%) and increased the cytotoxic effect of Cisplatin (68.18 to 87.56%). A single injection of VP-4 to mice stimulated the proliferative activity of spleen cells, studied ex vivo, units and partially restored their cytostatic-suppressed activity. The cytotoxic action of the spleen cells of immunized mice on tumor line cells YAC-1 was twice as great as that of spleen cells taken from intact animals and potentiated the cytotoxic action of Cisplatin. The mechanism of increasing the proliferative activity and cytotoxic effect of monomuclears under the influence of vaccine VP-4 is seemingly linked with the synthesis of cytokines, influencing the lymphokine-activated cytotoxicity of lymphocytes.