Transformation of single myeloid precursor cells by the malignant histiocytosis sarcoma virus (MHSV): Generation of growth‐factor‐independent myeloid colonies and permanent cell lines

Abstract

Direct single‐cell assays for oncogenic transformation are available for fibroblasts but not for other cell types. Using malignant histiocytosis sarcoma virus (MHSV), a member of the ras family of retroviruses, in vivo‐infected granulocyte/macrophage and macrophage precursor cells lost the requirement for externally added hematopoietic growth factors. Factor‐independent growth was demonstrated by colony‐transfer experiments. More than 25% of the independent colonies were established as permanent macrophage cell lines following a phase of adaptation to tissue culture conditions. Factor‐independent colony growth was also obtained by in vitro infection of single cells. As many as 50% of all mye..