The effect of 13-cis retinoic acid on hematopoiesis in human long-term bone marrow culture

The modulatory effect of 13-cis retinoic acid (RA) on the growth, differentiation and function of hematopoietic cells in human long-term cultures was studied. RA (5 X 10(-8) M) induced enhancement of myeloid progenitor cell growth in the non-adherent layer throughout 6 weeks of incubation while it did not affect the number of myeloid progenitors in the adherent layer. The vitamin did not alter the differentiation pattern of colony forming unit-culture (CFU-C). The addition of RA to cultures for 5 weeks did not alter the cellular composition of the adherent layer. Prolonged exposure of hematopoietic cells to RA did not affect the functional activity of neutrophils and macrophages, i.e. the cells were active in phagocytosing Candida albicans (CA).