Wirkung von 5-fluorouracil auf die Strahlensensibilität von granulozytopoetischen Stammzellen des Knochenmarks und des Blutes

: The radiation tolerance of haematopoietic stem-cells, originating from blood and bone marrow, after exposure to 5-Fluorouracil (5-FU) was investigated. The CFU-C Colony Formation Test was used to determine the surviving fraction of cryopreserved mononuclear bone marrow and blood cells, after incubation in culture medium containing 1 ng/ml 5-FU for 24 hours. With the same assay system we determined the radiation tolerance of peripheral CFU-C from three patients before and after 5-FU radio-chemotherapy (1000 mg/m2/24 h per day for four days), while the influence of the small radiotherapeutic treatment volume was neglected. Neither in the in vitro experiments nor in the patients we found a significant variation of the dose-survival curves with or without 5-FU. So it is concluded, that the enhanced myelodepression of 5-FU combined with radiation may be due to an additive effect or by effects on the microenvironment or on the pluripotent stem cell system.