Detection of Granulocyte Colony‐stimulating Factor Produced by a Newly Established Human Hepatoma Cell Line Using a Simple Bioassay System

A colony‐stimulating factor(CSF)‐producing tumor cell line (KX‐87) was established from a patient with hepatocellular carcinoma and marked granuloeytosis. This cell line formed tumors on nude mice in high frequency and the mice revealed marked granuloeytosis. In clonogenic assays of human bone marrow cells, KX‐87 conditioned medium (CM) supported the formation of colonies mainly consisting of neutrophilic granulocytes but had no burst‐promoting activity. The molecular weight of the colony‐stimulating activity (CSA) in KX‐87CM was estimated about 25,000 daltons by gel filtration and a new bioassay system. In principle, a subline of murine hemopoietic cell line NFS‐60 was cloned which was dependent on KX‐87CM. Then the growth of this subline was examined by a rapid and sensitive colorimetric tetrazolium assay. From these results, it was concluded that the CSA which KX‐87 cell line produced was G‐CSF.