THE EFFECTS OF ADRENOCORTICAL HORMONES, ADRENOCORTICOTROPHIC HORMONE AND PREGNANCY ON SKIN TRANSPLANTATION IMMUNITY IN MICE

Abstract

SUMMARY The median survival time of skin homografts on A or CBA mice is prolonged 50% by the injection of cortisone acetate 0·4 mg/day. Cortisol is as effective as cortisone; corticosterone, progesterone, testosterone, and oestradiol are ineffective, though corticosterone is more 'cortisonelike' in its action than the others. Deoxycorticosterone neither shortens the life of skin homografts nor interferes with the power of cortisone to prolong it. The injection of cortisone does not prevent a pre-existing state of transplantation immunity from taking effect. The action of cortisone is attributed partly to preventing the access of antigenic matter to regional lymph nodes and partly to an effect on the regional nodes themselves. The injection of 1 mg/day adrenocorticotrophic hormone (ACTH) in a slow-absorption medium has effects indistinguishable from the injection of 0·4 mg/day cortisone acetate. ACTH is ineffective in adrenalectomized mice, not excepting females whose ovaries have been luteinized by prior administration of chorionic gonadotrophin, and is not less effective in ovariectomized female mice than in normal. Female mice are slightly less responsive to cortisone and ACTH than males. Adrenalectomy as such does not influence the survival time of homografts, but causes them to become more strongly united to the graft bed and to elicit a brisker mesenchymal reaction. Transplantation immunity is not weakened by pregnancy in mice. Repeated heterospecific pregnancies neither elicit transplantation immunity nor weaken a state of immunity that is already in being. For reasons unconnected with pregnancy or parity, elderly female A-line mice react against homografts more feebly than CBA females of the same age. Species differences in the responses of animals to cortisone and ACTH are interpreted in terms of the composition of cortical secretions and the sensitivity of tissues to their action.