Abstract
The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on myeloid colony formation were investigated by initial and delayed addition of TPA to the cultures. In the human placental conditioned medium-stimulated cultures, TPA inhibited normal myeloid colony formation without any change in colony morphology when added at the beginning of culture. However, macrophage-like transformation of myeloid colonies by TPA was clearly observed after the delayed addition of TPA. Colonies and clusters already formed at the time of TPA addition were exclusively neutrophilic. Two days after TPA addition, many colonies apparently contained macrophage-like cells. Within 4 days after TPA addition, almost all myeloid colonies transformed into the macrophage type. Parallel study of initial and delayed addition of TPA revealed that this macrophage-like transformation of neutrophilic colonies occurred at high concentrations of TPA that would fully inhibit colony formation if added initially. TPA caused similar effects on leukemic colony formation.
Footnotes
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↵1 Supported in part by grants-in-aid for cancer research from the Ministry of Health and Welfare and from the Ministry of Education, Science, and Culture of Japan.
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↵2 To whom requests for reprints should be addressed, at Division of Hematology, the Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Hongo, Tokyo 113, Japan.
- Received July 26, 1982.
- Accepted January 14, 1983.
- ©1983 American Association for Cancer Research.
Volume 43, Issue 5
