ELECTROCHEMOTHERAPY WITH BLEOMYCIN IN SA-1 TUMOR-BEARING MICE - NATURAL-RESISTANCE AND IMMUNE RESPONSIVENESS

Electrochemotherapy is an antitumor treatment that utilizes locally de livered electric pulses to increase the effectiveness of chemotherapeu tic drugs in cells and tissues. Electric pulses permeabilize tumor cel ls to allow nonpermeant drugs such as bleomycin to enter the cells, Al though preclinical data indicate that immune responsiveness of the org anism is important for obtaining cures of the tumors after electrochem otherapy with bleomycin, it is not known how electrochemotherapy affec ts the immune system of the organism. The aim of the study was to dete rmine the effects of electrochemotherapy with bleomycin on natural res istance and immune responsiveness. Natural resistance was evaluated by phagocytic and intracellular killing activity (oxidative burst) in mo nocytes and polymorphonuclear granulocytes from Venous blood, and immu ne responsiveness by blast transformation of spleen mononuclear cells to mitogens. The percentage of monocytes in venous blood able to elici t oxidative burst was significantly increased 7 days after the electro chemotherapy and returned to normal values after 14 days. In addition, increased blast transformation of spleen mononuclear cells by stimula tion with concanavalin A (7 lymphocytes activity) was found 14 days af ter electrochemotherapy treatment. The results of our study demonstrat e that electrochemotherapy with bleomycin affects the immune system of the organism.