SUPEROXIDE-PRODUCING LIPOPROTEIN AS A FACTOR OF TUMOR-GROWTH SUPPRESSION, ENHANCEMENT OF LEUKOCYTE NUMBER, AND ACCELERATION OF CELL-DIVISION IN CULTURE

Intact rats were injected intraperitoneally four times with a superoxi de-producing lipoprotein which was isolated from human blood serum, pu rified, and activated by Fe3+ (suprol, 150 mu g/ml), and after 24 h an increase in peripheral blood leukocyte number by only 8-10% was obser ved. An injection of the active suprol into animals three days after i noculation of the Pliss lymphosarcoma or the M-1 sarcoma caused an inc rease in the leukocyte number approximating that of the intact (health y) animals. However, the growth of the M-1 sarcoma and the Pliss lymph osarcoma decreased by 31 +/- 4 and 52 +/- 2%, respectively. An additio n of active suprol (15 mu g/ml) into chick embryo cell culture during the steady-state growth phase stimulated the cell growth by 52.1%. Con centrations of active suprol above 50 mu g/ml caused the complete lysi s of the cells in culture. In control experiments Cu,Zn-superoxide dis mutase suppressed the suprol-stimulated cell growth in the actively pr oliferating culture, while inactive (native) suprol virtually failed t o enhance leukocyte number, to suppress growth of the above-mentioned tumors, and to stimulate cell growth in culture. These results suggest that superoxide radicals are likely to participate in these processes .