Differentiation of Abelson murine leukemia virus-infected promonocytic leukemia cells

Virus-producing, tumorigenic, promonocytic leukemia cell lines were derived from Abelson murine leukemia virus-infected mice. This study shows that, of these 25 cloned lines, 22 were capable of extensive differentiation. It also shows that granulocyte-macrophage colony-stimulating activity increased the proportion of differentiating cells in 17/22 lines. Cells from agar colonies with a diffuse colony morphology had an increased expression of mature macrophage phenotypic characteristics, and a reduced proliferative capacity in vitro, compared to cells from agar colonies with a compact colony morphology. Cells from diffuse colonies also produced less Abelson virus, and were less tumorigenic in vivo than cells from compact colonies. Together, these results suggest some Abelson virus-producing leukemic cells are not blocked in their capacity to differentiate and are capable of reversing the transformed phenotype.