Role of BPA and erythropoietin for BFU-E growth from Friend virus-infected mice.

The dependency of BFU-E growth in vitro on burst-promoting activity (BPA) was studied in F-MuLV-P-infected DBA/2 mice. As standard source of BPA, the supernatant of a mixed lymphocyte culture (MLC-BPA) was used in varying concentrations in the cultures of bone marrow and spleen cells. The serum content in the BFU-E cultures was reduced to 4% of fetal calf serum. This reduction had to be compensated in normal and F-MuL V-P-infected cell cultures by the addition of higher BPA concentrations. The results show that the F-MuL V-P infection did not abolish the dependency of BFU-E growth on BPA. Furthermore, in cultures with 4% of fetal calf serum and 20-30% of MLC-BPA about 50% of the BFU-E of normal mice grew without addition of erythropoietin. In virus-infected mice this number increased to about 100% in bone marrow and spleen. In F-MuL V-P resistant C57Bl/6 mice the percentage of BFU-E grown without addition of erythropoietin did not change after virus infection.