EFFECT OF FOCAL IRRADIATION ON HUMAN BONE MARROW

Abstract

The acute effect on hematopoiesis of focal irradiation to bone marrow was evaluated by serial morphologic studies of aspirates from irradiated and from distant marrow sites during radiotherapy of 9 patients with cancer. In the irradiated marrow, the erythroid line showed marked reduction of early precursors at 400 r and complete disappearance of all nucleated cells at 1,000 r. The granulocytic line did not demonstrate marked reduction of early forms until 1,000 r had been delivered; giant granulocytes were most prominent at 1,000 r. Marrow lymphocytes were surprisingly persistent in the irradiated marrow; preservation of lymphocytic foci was noted in histologic sections of marrow at 2,000 r. Monocytes demonstrated cytoplasmic vacuolation at 400 r and tended to persist even at 2,000 r. Megakaryocytes were rarely noted after 1,000 r marrow irradiation. Histologic sections of marrow particles confirmed the hypocellularity of irradiated marrow. Plasma cells and reticular cells proved to be resistant to these doses and were conspicuous in the histologic sections. Consistent changes were not noted in the nonirradiated marrow samples. A mild depression of circulating blood neutrophils, lymphocytes, and platelets occurred without evidence of degenerative changes in these elements. The absence of a radiation effect on the nonirradiated marrow may have been due to the relatively small volume of marrow irradiated in the treatment fields.