The in vitro and in vivo effect of recombinant interferon alpha-2a on circulating haemopoietic progenitors in polycythaemia vera.

In four patients with polycythaemia vera (PV) who received interferon alpha (IFN-alpha) (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-alpha 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-alpha on HPC from patients with myeloproliferative disorders. Significant improvement in the patients' clinical and haematological conditions should encourage larger studies on IFN-alpha administration in PV patients.