[en] In vitro cultures of granulocytic progenitor cells (CFU/sub c/) were made from both irradiated and non-irradiated bone marrow taken from patients exposed to radiotherapy for hematosarcoma at least 1 year before the culture. Five patients had limited subdiaphragmatic irradiation, and 4 had total lymphoid irradiation. In addition to the cloning rate per 10⁵ nucleated medullary cells which gives the medullary concentration in CFU/sub c/, the cloning rate per 10⁵ metamyelocytes has been established as an index of the effectiveness of the leukopoiesis. The total number of medullary CFU/sub c/ has been calculated and the validity and interest of this calculation are discussed. Medullary granulocytic regeneration in the irradiated zone depends, as for the erythrocytic line, on the medullary volume irradiated. It is practically zero in the irradiated zone in the case of a limited target volume, and significant in the case of total lymphoid irradiation. The number of CFU/sub c/ was found to be normal or subnormal a few years after treatment by mantle field radiotherapy only, but can be reduced when chemotherapy was used after irradiation. It was further reduced after total lymphoid irradiation. A decrease in the CFU/sub c/ compartment can coexist with a normal granulocyte blood count suggesting a compensatory mechanism involving a mitotic amplification between the progenitor cell and the final differentiated cell

[en] Thirty-two patients with lymphoma were treated by extended radiotherapy (RT) at a dose of 40 Gy and were studied by ferrokinetic studies and surface counting at various times following irradiation. Loss of hematopoietic activity in the irradiated areas is compensated by increased activity in the non-irradiated areas. Despite the return of peripheral blood counts to normal, the hyperactivity of the non-irradiated bone marrow persists over up to 13 years after RT, while the hematopoietic activity of the irradiated areas remains depressed and is only slightly higher than immediately after RT. The hypoactivity persisted even when the hemopoietic tissues had been subjected to the intense stimulation provoked by an aplasia caused by chemotherapy. However, a recovery was observed for dose of 20 Gy or lower. The hemopoietic activity of the irradiated bone marrow appears to be related to the volume of the marrow irradiated and is higher after a mantle + inverted Y field than after a mantle field. Bone marrow scintigraphies with ⁵⁹Fe in 7 out of 9 patients studied revealed an extension of hematopoiesis into a normally dormant area of the marrow, such as the femora. In 2 patients an erythropoietic activity was observed in spleens which had received a dose of 40 Gy, and extra medullary erythropoiesis was found in approximately two-thirds of the patients

[en] This paper presents further data obtained through ferrokinetic studies of patients having received either high doses (40 Gy) of radiotherapy to a limited field followed by autologous bone marrow transplantation, or moderate doses (20 Gy) to an extended bone marrow volume. (Auth.)

[en] Twenty-three patients with malignant lymphoma (13 cases of Hodgkin's disease and 10 cases of non-Hodgkin's Lymphoma) had their bone marrow studied based on a culture of medullary granulocytic progenitor cells (CFU/sub c/) in methylcellulose. The number of CFU/sub c/ per 10⁵ nucleated medullary cells, which measures the medullary concentration in CFU/sub c/, has been established. These results also have been expressed in terms of the number of CFU/sub c/ per 10⁵ metamyelocytes plated, an index which measures the effectiveness of the leukopoiesis. Additionally, the number of CFU/sub c/ per kg of body weight has been calculated. Before treatment, the number of CFU/sub c/ is significantly lower than in normal subjects. There is a normal or elevated number of circulating granulocytes in these patients which can be explained by means of a mitotic amplification between the progenitor cell and the final differentiated cell. Ten patients were studied immediately after completion of radiotherapy. The number of CFU/sub c/ returned from low to normal for 4 of them, remained low for 3 others, and was reduced from normal to below normal for the last 3. Four patients were studied between 6 and 8 months after radiotherapy. In all 4, the number of CFU/sub c/ returned to normal, whether they had been initially lowered by radiotherapy or not. This normalization resulted from an increase in the concentration of CFU/sub c/ in the non-irradiated zone, and for three of them resulted in part from a medullar regeneration in the irradiated zone