Hematopoietic stem cells in Friend murine leukemia virus infected mice undergoing chemotherapy: failure to eradicate Ep-independent erythropoiesis by BCNU.

DBA/2 mice, 12 days after infection with the polycythemia-inducing Friend virus (F-MulV-P), were treated with a single dose of BCNU. The effect of 35 mg/kg and lower doses on the different stem cell pools (CFUS, CFUC, CFUE) and the F-MulV-P specific ICPC (infectious centers producing cells) and Ep-independent CFUE was studied in detail. The depression of CFUS and CFUC was comparable in normal and F-MuLV-P infected mice. The CFUE population of virus infected mice, which had been completely Ep independent before treatment, showed only some normal Ep dependent colony growth thereafter. This finding was in contrast to the effect of multiple doses of Hydroxyurea, studied previously, which had given the same quantitative depression of CFUS and CFUC. Possible reasons for this failure are discussed; they may be the more proliferation independent mode of action of BCNU and the delayed hemopoietic regeneration.