Hematotoxicity of 5-fluorouracil and alpha-interferon on the human normal hemopoietic progenitors

The toxic effects of a combination of 5 fluorouracil (5-FU) and interferon alpha on normal human hemopoietic progenitors were assessed in vitro. CFU-GM growth was evaluated following 1 h incubation of bone marrow cell suspension with 5-FU 100 micrograms/ml or IFN-alpha 2a 1000 U/ml, or with both drugs, either simultaneously or sequentially added. IFN-alpha did not show toxic effects on normal human hemopoietic progenitors and the severe toxicity of 5-FU on the latter was not modified by IFN-alpha. These results suggest that the changes observed in vivo of 5-FU toxicity induced by IFN-alpha should be attributed to indirect effects of the latter.