Correlation between production of colony-stimulating activity (CSA) and adipose conversion in a murine marrow-derived preadipocyte line (H-1/A).

The correlation between adipose conversion of cloned H-1 cells (H-1/A) and their production of colony-stimulating activity (CSA) was examined. The production of CSA from H-1/A cells declined after adipose conversion, although H-1/A cells are active producers of CSA during their fibrocytic stage. The addition of 2 X 10(-5) M 5-bromo-2'-deoxyuridine to the cultures almost completely inhibited adipose conversion and there was no reduction of CSA levels after 9 days of culture. On the other hand, the addition of 10(-6) M hydrocortisone sodium succinate to the culture markedly enhanced adipose conversion, and a greater reduction in the CSA level was observed in the supernatants than in the control cultures after 12 days of culture. Indomethacin had no effect on the production of CSA or on adipose conversion. Furthermore, there were no significant differences between the CSA levels of nondialyzed supernatants and dialyzed supernatants from the control cultures during the entire course of the experiment. Supernatants during the adipocyte stage of H-1/A cultures did not inhibit the CSA derived from the fibrocytic stage. There were no differences in colonies in agar cultures stimulated by supernatants derived from cultures that had undergone either of the above treatments. These results suggest that the reduction of CSA is not due to the production of inhibitors, but that the production of CSA declines after adipose conversion of H-1/A cells. Preadipocytes in bone marrow therefore appear to contribute to granulopoiesis during the fibrocytic stage and are hematopoietically inactive when they convert to adipocytes.