In vitro hemopoiesis of marrow cells from myelodysplastic patients: effects of mitogen-stimulated spleen cell-conditioned medium and vitamin A and D derivatives.

We determined the ability of pokeweed mitogen-stimulated human spleen cells to support the growth and proliferation of hemopoietic progenitors from normal and myelodysplastic syndrome (MDS) patients, in the presence and absence of the maturation-inducing agents 13-cis-retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (vit D). The addition of various concentrations of vit D or RA to culture plates containing MDS patients' marrow cells stimulated myeloid colony growth. A higher number of myeloid colony-forming units-cell was noted in cultures containing vit D or RA in addition to pokeweed mitogen spleen-conditioned medium compared to these substances and placenta conditioned medium. When colony-forming units-cell from MDS patients was incubated with 2 X 10(-8) M vit D the percentage of monocyte-macrophage colonies was increased and the number of granulocyte colonies was decreased. Neither vit D nor RA affected the number of cells per colony. Our findings suggest that pokeweed mitogen spleen-conditioned medium provides a more potent source than placenta-conditioned medium for humoral factors that stimulate the growth of hemopoietic progenitors from MDS patients and that the use of pokeweed mitogen spleen-conditioned medium may improve studies of hemopoiesis in MDS patients.