THE INFLUENCE OF VARIOUS HORMONES ON THE RETICULO-ENDOTHELIAL SYSTEM: ENDOCRINE CONTROL OF BODY DEFENCE

Abstract

SUMMARY (1) The three principal natural oestrogens, oestrone, oestriol and 17β-oestradiol, are strong stimulants of the reticulo-endothelial system (RES). (2) Testosterone had no effect on the RES when administered alone. Doses of testosterone which inhibited the oestrogenic response of the reproductive tract to oestrone and oestriol also inhibited the stimulant effect of these oestrogens on the RES. In contrast, testosterone markedly potentiated the stimulant effect of 17β-oestradiol on the RES even in doses at which the oestrogenic response is inhibited. These results imply that 17β-oestradiol is the principal oestrogen concerned in the control of RES activity, and provide further proof that the oestrogen molecule has two biological activities, one acting on the RES and the other on the reproductive tract, and that they act independently although contained in the same molecule. (3) Progesterone is a mild RE stimulant. Doses which inhibited the oestrogenic response of the reproductive tract did not affect oestrogen-produced RE stimulation. (4) Small doses of cortisone stimulated the RES, but high doses depressed RE activity and oestrogen-produced RE stimulation. (5) Thyroxine had no effect on the RES when acting alone, but markedly potentiates oestrogen-produced RE stimulation. (6) The hormones of the anterior lobe of the pituitary are all stimulants of the RES; and, with the exception of growth hormone and follicle stimulating hormone, acted in a synergistic manner with oestrogen. (7) The hormones of the posterior lobe of the pituitary had no effect on the RES. (8) The results as a whole indicate that the endocrine system exerts a homeostatic influence on RE function, and that 17β-oestradiol is the principal stimulant of the RES and body defence.