Control system of proliferation of thrombocytopoietic cells in mice and the effect of x-irradiation

Effects of thrombocytopoietic accelerators and inhibitors were decided from the aspects of active changes of thrombocytopoietic activity at the phase of megakaryocytes from the whole body of experimental animals using circulating thrombocytes labeled with 75Se-methionine (75SeM), and the effects of X-irradiation were studied. Thrombocytes producibility was supressed after transfusion of twice number of total thrombocytes in normal mice. When a proper quantity of anti thrombocyte serum (ATS) is administered, thrombocytopoiesis is promoted. Changes of thrombocytopoietic activity in megakaryocytes by whole body X-ray irradiation indicated dose dependence. Changes of thrombocyte number were similar to those which might be observed after the incorporation of ATS. The labeling of thrombocytes with 75SeM indicated a maximum activity, eight months after thrombocyte number got minimized. From these results, it was found that a special control system, of which medium is humoral factor, acts in thrombocytopoietic changes which are observed at the period of acute radiation injury. (Serizawa, K.)