The ability of A-MuLV to transform bone marrow cells on in vitro culture in agarose is enhanced by inclusion of conditioned media during infection and culture. The conditioned medium of a non-virus producing A-MuLV transformed fibroblast cell line was synergistic with medium from Whitlock-Witte long-term bone marrow cultures, while conditioned medium from modified Dexter-type cultures was not active. These media all contained growth promoting activity for bone marrow cells. There are two type of transformed colonies produced, and transformation of only one type was enhanced by inclusion of conditioned media. Analysis of this type of transformed cell showed them to be pre-B cells. Limiting dilution analysis suggests that transformation process to be dependent on two types of cells, one presumably the target and the second an "accessory cell". Models are presented to account for the factor-dependent in vitro transformation of pre-B cells.
- Abelson murine luekemia virus
- Pre-B cell
- Whitlock-Witte cultures
- accessory cell-dependent transformation
- in vitro transformation
ASJC Scopus subject areas
- Cancer Research