Thymus Cell Death Following Irradiation

Abstract

JACKSON, K. L., CHRISTENSEN, G. M., AND FORKEY, D. J. Thymus Cell Death following Irradiation. Radiation Res. 34, 366-377, (1968). Rat thymocytes were studied in vivo and in vitro following 1000 R of Xirradiation to determine whether in vivo loss of nucleated cells is due primarily to mitotic inhibition or to interphase death. In vivo the rate of loss of live nucleated cells exceeded the rate of loss of total nucleated cells, and both rates exceeded that predicted on the basis of inhibition of cell division, implicating interphase death as a mechanism. Total thymus DNA decreased, but DNA associated with cell debris increased after irradiation, suggesting that cells killed by irradiation undergo lysis and that the resulting cell debris is removed more slowly than the cells break down. After in vitro irradiation thymocytes died in interphase at the same rate that live cells disappeared from the gland after in vivo exposure. It is concluded that the major mechanism for cell loss from rat thymus following whole-body exposure is radiation-induced interphase death followed by cell lysis.