Experimental Immunologic Adrenal Injury

Twenty-three unilaterally adrenalectomized guinea pigs were injected with autologous and homologous adrenal tissue homogenates respectively, in Freund's adjuvant. Widespread adrenal lesions were found in 10 of 12 animals receiving auto-antigen and to a lesser extent in 6 of 11 animals injected with homologous pooled antigen. Widespread systemic lesions were present in both these and in control animals receiving Freund's adjuvant alone. These latter animals showed no adrenal involvement. The early changes within the adrenal consisted of perisinusoidal cellular proliferations in the deeper layers of the cortex. Focal granulomata developing at a later stage tended to become confluent and to displace cortical cells. Some loss of these cells was attributable to ischemic injury. The localization in the deep fasciculata and reticularis was thought to depend (a) on the varying antigenicity of adrenal cortical components, (b) the possible inhibitory effect of antiphlogistic adrenal cortical hormones on the development of lesions in the outer cortex, and (c) the presence of littoral cells in the deep cortex. These cells are thought to be involved in the mediation of the stimulus initiating differentiation of primitive mesenchymal cells in response to a circulating auto-antigen. The medullary lesions may be related to the presence of ectopic reticularis cells in this location. It was suggested that the cellular response in the target organ to injections of adrenal homogenates may denote a specific "organ-self" recognition mechanism involving an immune (i.e. defensive) reaction. It was postulated that this may be an accentuation of the physiological function of immunologically competent cells. Their proliferation, under normal circumstances, would prevent by means of production of "binding" globulins, the escape and dissemination of endogenous freed adrenal antigens into the circulation. Although the experimental stimulus arose from without the gland, by virtue of the presence of a circulating adjuvant-bound antigen, the adrenal reaction followed the same pattern as would obtain if the antigen was liberated within the suprarenal cortex.