Although the biological mechanism of recombinant IFN in the treatment of PV is not completely understood, evidence to suggest promotion of immunoregulatory cell function, inhibition of angiogenesis, induction of pro-apoptotic gene expression, alteration of the bone marrow microenvironment, suppression of hematopoietic progenitor cells, and increase cycling of hematopoietic stem cells (HSC) has been reported.