Characterization of colony-stimulating activity in medium conditioned by a human cell line (KSNY)

A human lung cancer cell line (KSNY) produces a high level of human colony-stimulating activity (CSA) as shown by the dose-response relationship between the number of colonies and the concentration of conditioned medium (CM). The CM tends to induce markedly granulocytic colonies rather than other cell-type colonies. The medium conditioned by KSNY cells (KSNY-CM) is stable at 50 degrees, but is completely inactivated at 70 degrees for 30 min. There is little binding of mouse CSA and/or human CSA in the CM to concanavalin-A-Sepharose. Fractionation of the CM by Sephacryl S-200 chromatography indicated that the maximum activity of KSNY-CSA for mouse and human marrow cells is eluted at approximately 20,000 approximately 25,000 and at 45,000 approximately 48,000 daltons.