[Possible role of Bac. megaterium H antigens common with tumor antigens in the increase of the antitumor activity of lymphocytes].

The antitumour cytotoxic activity of lymphocytes is shown to increase both with inoculation of antigens contained in tumour cells and under the influence of microbial Bac. megaterium H., culture, its ultrasonic homogenate, cell walls and cytoplasmic preparation. Certain cytoplasmic fractions of Bac. megaterium H, like other microbial and tissue antigens having no similarity with tumour cells, did not produce such an effect. An assumption is advanced that the increase in the antitumour cytotoxicity of lymphocytes under the influence of Bac. megaterium H is due to the cross-reacting antigens contained in the microbial cell and blastoma tissue.