| pubmed-article:3303160 | pubmed:abstractText | The early response of blood cells to irradiation has been studied in leukemia patients who received total body irradiation (TBI) prior to cyclophosphamide and bone marrow transplantation. After a single session treatment (10 Gy in 4 h) the most dramatic variation was observed in the granulocytes. At the end of the irradiation their concentration was 2 to 6 times higher. Because of a subsequent rapid decline, the peak may be overlooked if the blood counts are delayed. Lymphocytes decreased to 50% at the end of the single session TBI and continue to decrease exponentially, with a half time of 30 h. During a fractionated irradiation (11 X 1.2 Gy in 4 days) the lymphocyte number dropped to 60%, 13 h after the first fraction and this decline continued with a half time of 30 h during the treatment. From the data obtained in vivo, a lymphocyte D0 value of 1.2 Gy was computed. The lymphocyte subsets (B.T. OKT4 OKT8) did not exhibit different radiosensitivities either in vivo or in vitro. The disappearance of lethally hit lymphocytes from the blood exhibits a biphasic kinetic: 50% of the cells disappear in a few hours and 50% with a half time at 30 h. Lymphocytes irradiated either in vitro or in vivo when in culture disappear slowly, contrasting with the in vivo findings. It may suggest that lethally hit lymphocytes are quickly removed from the circulating pool in vivo. | lld:pubmed |
