EFFECTS OF NATURAL HUMAN INTERLEUKIN-6 ON THROMBOPOIESIS AND TUMOR PROGRESSION IN TUMOR-BEARING MICE

The growth of inoculated colon 26 adenocarcinoma (colon 26) in mice gr adually increased the platelet count owing to murine IL-6 secreted fro m the tumor, while Lewis lung carcinoma (LLC) decreased the platelet c ount in the hosts, depending on the tumor growth. Natural human IL-6 i njections (hIL-6), 280 mu g/kg/day, stimulated the platelet production in both types of carcinoma-bearing mice. When the administration of m itomycin C or cisplatin decreased the platelet number as a side reacti on with a concomitant of suppressing the growth of colon 26 and LLC, r espectively, hIL-6 could also increase the platelet count without the augmentation of tumor growth. However, loss of carcass weight was obse rved in colon 26-bearing mice treated with hIL-6, suggesting the devel opment of cachexia is associated with hIL-6 administration. Despite th e possibility of inducing cachexia in some types of tumors, our result s suggest that IL-6 could be a useful means of restoring the decreased platelet number in cancer patients after intensive chemotherapy.