Effect of co-administration of granulocyte colony-stimulating factor on interferon therapy

The effect of co-administration of granulocyte colony-stimulating factor (G-CSF), as an antineutropenia agent, on interferon therapy was examined in a mouse model, in anticipation of an enhancement of interferon efficacy, because neutrophils induced by G-CSF are thought to act as antitumor effectors. G-CSF was intraperitoneally co-administered with human interferon alpha A/D (IFN) on Day 6 to Day 10 after intradermal inoculation of Meth A fibrosarcoma. Although the co-administration of G-CSF could protect against neutropenia and leukopenia induced by IFN, it did not enhance the regression of tumor, and rather reduced the prolongation of survival time and the long-term survival incidence of IFN therapy. The subsequent in vitro study showed that the antiproliferative activity of peripheral blood leukocytes from Meth A-bearing mice given both IFN and G-CSF was much weaker than that of mice given IFN alone. Whether the observed nullifying effect of G-CSF on IFN therapy is also the case with tumors other than Meth A is open to further study.