Glucocorticoid-induced membrane alteration of thymocytes and thymic phagocytosis

Electrophoretic mobility (EPM) of thymocytes progressively decreased after an i.p. injection of 10 mg hydrocortisone, and reached its lowest value 3 hr later. The degree of the decrease in the EPM of thymocytes was dependent on the dose of hydrocortisone. Thymic phagocytic cells began to ingest thymocytes in vivo 2 hr after hydrocortisone injection, and thymic phagocytosis continued up to 8 hr. Glucocorticoid-induced phagocytosis was also detected in vitro, i.e., primarily cultured thymic phagocytic cells ingested membrane-altered viable thymocytes from 10-mg hydrocortisone-treated mice 4 to 10 times more than control thymocytes. It was considered from these results that the decrease in the negative surface charge of thymocytes is closely associated with the phagocytosis of thymocytes by thymic phagocytic cells.