Effect of recombinant gamma interferon on chronic myelogenous leukemia bone marrow progenitors

In order to understand its mechanism of action and explore its potential as a therapeutic agent, we studied the effect of recombinant gamma interferon (IFN) on in vitro proliferation and on karyotype of bone marrow-derived hematopoietic stem cell progenitors (BFUe, CFUmix) obtained from patients with Ph1-positive chronic myelogenous leukemia (CML). Addition of IFN to culture resulted in a dose-dependent inhibition of both normal and CML BFUe and CFUmix. The maximum dose-dependent suppression of CML BFUe (92% +/- 4%) and CML CFUmix (100%) exceeded the maximum suppression of normal BFUe (40% +/- 4%) and normal CFU mix (68% +/- 6%) (p less than 0.001 and p = 0.008). In parallel studies, CML BFUe and CFUmix were cultured with and without IFN, and cells recovered from culture were examined cytogenetically. Treatment of CML bone marrow cells (BMC) with IFN resulted in an increase in the proportion (p less than 0.001) of Ph1-negative metaphases when compared to control cells grown in the absence of IFN. Recombinant gamma interferon has a significant antiproliferative effect against CML bone marrow-derived stem cell progenitors in vitro, and the addition of this agent to culture increases our ability to identify a cell population derived from a Ph1-negative progenitor pool. Recombinant gamma interferon may selectively spare Ph1-negative hematopoietic progenitors, and may be an active agent in the treatment of CML.