Establishment of Megakaryoblastic Cell Lines by Coinfection of Abelson Murine Leukemia Virus and Recombinant SV40‐retrovirus

Murine embryonic cells including yolk sac prepared from 8‐day embryos were co‐infected with Abelson murine leukemia virus (A‐MuLV) and/or a recombinant retrovirus containing large T and small t antigens, and early region of simian virus 40 (M‐SV40). By coinfection with A‐MuLV and M‐SV40, megakaryoblastic cells were obtained in addition to mast cells and fibroblastic cells. However, following infection with A‐MuLV or M‐SV40 alone, no megakaryoblastic cells were detected, although mast cells and/or fibroblastic cells developed. The same results were obtained in several experiments. By single‐cell transfer, 6 acetyl‐cholinesterase (AchE)‐positive clonal cell lines were established. Characteristics of megakaryocytes, such as AchE, glycoproteins lIb and IlIa, and platelet peroxidase were detected in two representative cells (C1 and C8). More significant changes expressing differentiation were observed following treatment with phorbol myristate acetate or pokeweed mitogen‐stimulated murine spleen cell conditioned medium, although release of platelets was not observed. This is the first report showing development of megakaryocytic cells as the result of coinfection with retroviruses.