ERYTHROPOIETIN PRODUCTION BY HUMAN RENAL CARCINOMA CELLS IN CULTURE

Cells from human renal tumors were grown in monolayer cultures, and the media obtained at each medium change were assayed for erythropoietin activity. The medium from carcinoma I (a granular cell tumor) contained a high level of activity initially. The concentration of erythropoietin activity decreased with time in culture, but was significantly higher than that in controls after 4 mo. in vitro. There was also evidence of an inhibitory material present in the culture media. The activity formed by the tumor cells could be neutralized by an antibody to human urinary erythropoietin. The difference between activity measured in marrow cell cultures and that found by in vivo assay, and the chromatographic properties of the active preparation, suggest that the tumor-derived activity may be largely asialoerythropoietin. Two other renal carcinomas, of a different cellular type, produced significant erythropoietic activity.