Interferon gamma induces differentiation of cells from patients with myelodysplastic syndromes in vitro and in vivo.

A recombinant human interferon-gamma (IFN-gamma) was added to the clonal and suspension cultures of bone marrow (BM) cells from three patients with refractory anemia with excess of blasts (RAEB) before and after IFN-gamma therapy. IFN-gamma inhibited the hematopoietic progenitor cell growth from normal BM in one patient. In the remaining two patients with RAEB, IFN-gamma at lower concentrations (10-10(2) U/ml) consistently enhanced the growth of hematopoietic progenitors. The addition of IFN-gamma to suspension cultures promoted cellular differentiation in all three cases, as evidenced by persisting cytogenetic changes, Auer-rod containing maturing cells and cytochemical studies. Although IFN-gamma therapy resulted in partial or minor responses, these findings suggest the potential of IFN-gamma to act as an inducer of differentiation in myelodysplastic syndromes both in vitro and in vivo.