The in vitro and in vivo effect of recombinant interferon α‐2a on circulating haemopoietic progenitors in polycythaemia vera

Summary In four patients with polycythaemia vera (PV) who received interferon alpha (IFN-α) (3 MU subcutaneously three times a week) for 5 months, peripheral blood levels of granulocyte-macrophage colony-forming units and erythroid burst-forming units were assessed monthly. Circulating progenitors significantly decreased throughout the treatment period. Moreover, we observed an inhibitory activity of IFN-α on haemopoietic progenitor cells (HPC) from patients with PV in vitro. The data presented confirm previous research which has shown an inhibitory effect of IFN-α on HPC from patients with myeloproliferative disorders. Significant improvement in the patients’clinical and haematological conditions should encourage larger studies on IFN-α administration in PV patients.