The effect of Rauscher murine leukemia virus infection on the hemopoietic system of BALB/c mice. Cell proliferation and cell loss.

Cell proliferation was investigated in normal and Rauscher Leukemia Virus-infected BALB/c mice. Five days after inoculation, islands of leukemic blasts arose in the red pulp, and proliferated as shown by autoradiographic analysis after a pulse of 3H-Thymidine. These cells subsequently infiltrated the whole spleen and 3 weeks after infection about 60% of the spleen consisted of large immature erythroblast-like cells. Repeated injections of 3H-Thymidine led to uniform labeling of 85% of the spleen cells. Cell cycle analysis showed that for bone marrow as well as for spleen cells the total duration of the cell cycle did not differ from the cell cycle times of normal erythroblasts. From the difference between the actual doubling time and the potential doubling time (estimated on the basis of the cell cycle time) it can be calculated that considerable cell loss must occur. This cell loss is only to a minor extent due to the release of blasts into the peripheral blood. Probably cell death and extrusion of nuclei during erythroid differentiation are the main factors involved.