THYMIC PHAGOCYTOSIS AND REDUCTION IN THE NEGATIVE SURFACE-CHARGE OF THYMOCYTES AFTER X-IRRADIATION

X irradiation of thymocytes in vivo or in vitro caused the reduction of their electrophoretic mobility wthin 2 hr. An enhanced attachment of irradiated thymocytes to cultured peritoneal macrophages was noted 2 hr after whole-body irradiation. Thymic esterase-positive cells began to phagocytize thymocytes 2 hr after whole-body irradiation with 170 R. Since all of these three radiation-induced phenomena began to occur simultaneously shortly after irradiation, it was considered that the decrease in the negative surface charge of irradiated thymocytes enhanced the attachment of the thymocytes to thymic phagocytic cells through the reduction of the electrostatic repulsive forces and facilitated the phagocytosis of thymocytes by thymic phagocytic esterase-positive cells.