Simian virus 40-transformed adherent cells from human long-term marrow cultures: cloned cell lines produce cells with stromal and hematopoietic characteristics.

Adherent cells from long-term marrow cultures from 23 individuals were transformed with wild-type simian virus 40 (SV40). After transformation, cloned cell lines were developed that even after rigorous subcloning invariably produced both stromal cells and round cells. The stromal cells expressed cytoskeletal filaments similar to those of long-term marrow culture adherent cells and produced interstitial and basal lamina collagen types. The round cells had the electron microscopic appearance of primitive hematopoietic cells and when examined with cytochemical stains and monoclonal antibodies to hematopoietic differentiation antigens had reaction patterns suggestive of cells from several lineages. Most round cells expressed the pan-hematopoietic T-200 determinant, and lesser percentages expressed the early T cell antigens CD-1 and CD-3, HLA-DR determinants, the monocytic antigen recognized by Leu M3, and the myeloid antigens detected by monoclonal antibodies 1G10 and 12.8. In addition, when plated in semisolid medium in the presence of a source of colony-stimulating activity, up to 11% of the cells formed colonies consisting of blastlike cells that also expressed hematopoietic cell surface determinants. The data suggest that adherent cells in long-term marrow cultures contain a cell that after transformation by SV40 obligately produces cells with hematopoietic as well as stromalike features.