THE ROLE OF PERITONEAL-MACROPHAGES IN THE IMPLEMENTATION OF THE GROWTH-INHIBITORY ACTION OF GLUCOCORTICOIDS ON THE MOUSE HEPATOMA-22 CELLS - INFLUENCE OF HYDROCORTISONE ON THE CYTOTOXIC ACTIVITY AND PHOSPHOLIPID-METABOLISM OF MACROPHAGES

A single injection of hydrocortisone to mice with ascites hepatoma 22 does not substantially affect tumor growth. Inhibition of tumor growth is observed only when the ascites hepatoma is reinoculated into animals that had received no less than eight daily injections of hydrocortisone. It was shown that a single injection of hydrocortisone leads to suppression of the cytotoxic function and a decrease in the rate of phospholipid metabolism in the peritoneal macrophages. On the contrary, prolonged administration of the hormone induces a significant activation of the cytotoxic function of macrophages. Moreover, the incorporation of P-32 into the phospholipids of macrophages is restored practically to the control level. It is suggested that one of the mechanisms underlying the inhibitory effect of glucorticoids on macrophages is an inhibition of phospholipid turnover. Probably prolonged administration of the hormone leads to the formation of a macrophage population insensitive to the inhibitory action of glucocorticoids and distinguished by increased cytostatic activity. The appearance of such activated macrophages may be one of the causes of the enhancement of the cytostatic effect of hydrocortisone on tumor cells in the case of prolonged administration of the hormone.