Response of some hydrolases in thymus and lymphosarcoma of rats to injection of adrenal steroid hormones.

The acute degenerative alterations produced in lymphoid tissue of several species following a single injection of glycogenic adrenal cortical steroids, and the concomittant lymphopenia, were described in detail by Dougherty and White."' Subsequently, numerous investigators have been concerned with the biochemical effects of these steroid hormones on lymphoid tissue in efforts to elucidate the mode of action of corticosteroids.C f. 8-2 The changes induced by adrenal steroids in lymphocytes, initially termed lymphocytolysis' and subsequently more precisely described by the term lymphocytokaryorrhexis,21 with the resultant decrease in size of lymphoid organs, pointed to a possible relationship of these morphological alterations to the activity of certain hydrolases. De Duve and his colleagues"'2 have suggested that lysosomal hydrolases have a significant role in degenerative changes seen in a number of tissues. This led to our study of a possible correlation between the alterations in morphology and thymic size and the increased release of a group of thymic hydrolases in rats injected with cortisol. It has also been reported that the administration of a corticosteroid increased RNase activity in rat thymus' and in a corticosteroid sensitive transplantable lymphosarcoma in mice.'7"8 In contrast, a steroid insensitive lymphosarcoma did not show elevated RNase activity after hormone injection."7'18 It was suggested that RNase in lymphoid tissue may be of major importance in the glucocorticoid induced involution of these tissues. The present communication reports data obtained in an extension of our previous preliminary studies of rat thymic tissue' and also includes certain comparative studies with a transplantable lymphosarcoma.