Different haematopoietic growth factors have different capacity in overcoming the in vitro interferon gamma‐induced suppression of bone marrow progenitor cells

: Interferon gamma (IFNγ) inhibits haematopoiesis in vitro and an in vivo role in bone marrow suppression has been implied from clinical studies. We investigated the capacity of three recombinant (r), human (h), haematopoietic growth factors to overcome the in vitro IFNγ inhibition of bone marrow progenitor cells in a methylcellulose culture system. Granulocyte macrophage-colony stimulating factor (GM-CSF) partially reversed IFNγ-induced suppression of granulocyte-macrophage colony formation, by increasing colony forming units-granulocyte macrophage (CFU-GM) in a proportion ranging from 54–101%. Interleukin-3 (IL-3) and granulocytecolony stimulating factor (G-CSF) were much less effective. For erythropoiesis, IL-3 was much more effective and partially reversed IFNγ-mediated inhibition by increasing burst forming units-erythroid (BFU-E) in a proportion ranging from 52–138%. GM-CSF and G-CSF had no significant effect on IFNγ-induced suppression of BFU-E. In conclusion, haematopoietic growth factors have different capacity to overcome IFNγ-induced suppression of marrow progenitor cells in vitro. The findings may have therapeutic implications, as combinations of growth factors may be more effective in treating bone marrow failure syndromes.