Quantitative Aspects of Post-Irradiation Granulocytic Recovery The Effect of the Erythropoietic Suppression Subsequent to Hypoxia and Hypertransfusion

The postirradiation recovery of the myeloid system of normal and hypoxia pretreated mice was studied by quantitative means. In contrast to normal mice, the myeloid system of which recovered with a rise-fall-rise pattern, the hypoxia pretreated irradiated mice showed a sustained recovery with an earlier return of cell numbers to the normal level. Quantitative measurement of the ‘available pool’ of mature neutrophils revealed an enhanced production of neutrophilic granulocytes in mice pretreated with hypoxia. The effect of erythropoietic suppression, which occurs in these mice after cessation of hypoxia, on the myeloid recovery was also studied in mice made polycythaemic by hypertransfusion. The suppression of erythropoiesis per se seems not to be entirely responsible for the improved recovery of the myeloid system. The possible nature of the described changes in the myeloid recovery and their role with regard to the improved survival of posthypoxic mice are discussed.