Effects of myeloproliferative sarcoma virus on the pluripotential stem cell and granulocyte precursor cell populations of DBA/2 mice.

The hematopoietic stem cell (CFU-S) and granulocyte precursor cell (CFU-C) populations have been assayed in the spleen, blood, and bone marrow of DBA/2 mice at various times after infection with the myeloproliferative sarcoma virus (MPSV). Beginning between 7 and 19 days after virus infection, the number of CFU-S showed a steady, parallel increase in the blood and spleen, reaching a maximum at both sites by days 25-30. At the maximum, in the spleen the concentration of CFU-S was 10 times greater than that in the blood, and the total number of CFU-S was over 100 times greater than that of normal animals. During the same period, in the bone marrow the number of CFU-S decreased to one-half of normal. Nevertheless, the CFU-S from MPSV-infected animals differentiated normally in the spleens of irradiated, normal recipient mice (except for some hyperplasia of the erythroid component of spleen colonies). The CFU-C content of the bone marrow, spleen, and blood paralleled the CFU-S content of these organs: The CFU-S and CFU-C populations changed almost synchronously after MPSV infection. In the terminal stage of the MPSV-induced disease, a variable proportion of the CFU-C population acquired the ability to differentiate in the absence of added colony-stimulating factor.