In vitro induction of continuous acute promyelocytic leukemia cell lines by Friend or Abelson murine leukemia virus.

Long-term adult NIH 1 Swiss mouse bone marrow cultures (2.0 X 1 0 cells/ 1 OmI Corning flask. Fisher’s medium. 25 % horse serum. 1 07-M hydrocortisone) were infected with RNA type-C viruses at wk 4. and weekly removed cells were assayed for number. morphology. granulocyte-macrophage progenitor cells (CFUc). pluripotent hemopoietic stem cells (CFUs). and growth in liquid culture in 1 0 % WEHI-3 CSF. Cultures infected with Friend leukemia virus. anemia-inducing strain (Fly-A). showed increased CFUc 3 wk after virus addition. and removed nonadherent cells from 40 % of cultures grew as continuous lines. Each of 1 2 0.8 % methyl-cellulose-cloned sublines from one line (Fly-A 1 6-lV) showed CSF independence. promyelocyte morphology. and synthesis of esterase-M (ASD-chloroacetate substrate), myeloperoxidase. and lysozyme (2.0-10.0 sg/1O’ cells/24 hr); each contained 2 % -1 0 % cells with mature granulocyte morphology; and each caused acute myelogenous leukemia in adult mice. Four of eight cultures inoculated with Abelson murine leukemia virus (A-MuLV) with Moloney-MuLV helper virus coat produced CSF-independent basophilic promyelocytic leukemia lines by 5 wk after addition of virus. In contrast, cultures infected with long-latent-period leukemogenic viruses (BALB:virus-1 or Rauscher-MuLV) produced increased numbers of immature granulocytic cells for 20 wk. which, although not establishing as continuous lines, were morphologically dysplastic as compared with control uninfected cultures. Distinguishable grades of virus-specific granulocyte transformation were detected in corticosteroid-treated long-term marrow culture.