The in vitro effect of human recombinant interferon α (IFN) alone and in combination were studied on granulomonocytic colony forming units (CFU-GM) from the peripheral blood of 10 Ph1+ chronic myeloid leukemia (CML) patients and from the marrow of 5 normal or non-leukemic subjects. α- and γ-IFN alone determined a slight inhibition on colony growth with a preferential effect on "pure" macrophagic colonies. At maximum concentration (104 U/ml) leukemic colony inhibition was 46±34% for αIFN and 43±19% for γIFN. Culture growth with α + γIFN in combination were significantly inhibited (up to 96±4%) with a concentration-related effect. Similar results were obtained with normal CFU-GM. The synergism that was found in vitro is probably relevant for the in vivo therapeutic effects of these compounds in CML and suggest that the combination is worth testing in vivo.
- Hemopoietic progenitors
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