[Superoxide-producing lipoprotein as a tumor growth suppressing factor, increasing the number of leukocytes and accelerating cell division in culture].

Superoxide-generating lipoprotein was isolated and purified from human serum; four intraperitoneal injections of Fe(3+)-activated suprol (150 micrograms/ml) increased rat peripheral blood leukocytes only by 8-10% in 24 h. In 3 days after inoculation of animals with Pliss lymphosarcoma or M-1 sarcoma, similar injections of activated suprol increased leukocyte count up to the numbers in healthy animals. Growth of M-1 sarcoma and Pliss sarcoma was decreased by 31 +/- 4 and 52 +/- 2%, respectively. Activated suprol (15 micrograms/ml) stimulated growth of stationary chicken embryonic cell culture by 52.1%. Activated suprol at concentrations exceeding 50 micrograms/ml lysed all cells in the culture. Cu,Zn-superoxide dismutase suppressed suprol-stimulated proliferation of actively proliferating culture; not activated (native) suprol did not significantly increase leukocyte count, did not suppress tumor growth, and did not stimulate growth of cultured cells. The data suggest an important role of superoxide radicals in these processes. Inhibition of tumor growth by suprol may be associated with tumor DNA degradation by superoxide radicals (tumor DNA is more sensitive to O2- because superoxide dismutase activity is significantly lower in tumor cells versus normal tissues) and increased resistance of the organism due to stimulation of leukopoiesis.