EFFECT OF A HEMATOPOIETIC-PROMOTING FACTOR DERIVED FROM PORCINE KIDNEY ON MEGAKARYOCYTE COLONY FORMATION BY MURINE BONE-MARROW CELLS

We investigated the effect of a hematopoietic-promoting factor (HPF) purified from porcine kidney on murine megakaryocyte colony formation. Murine bone marrow cells were cultured in agar in Iscove's modified Dulbecco's medium supplemented with 10% fetal calf serum in the presence of interleukin-3 (IL-3) as a source of megakaryocyte colony-stimulating factor. HPF alone exerted only a slight effect on megakaryocyte colony formation, and the combination of HPF with IL-3 enhanced colony formation compared with IL-3 alone. At days 11 and 13, 1.9-fold and 1.7-fold enhancements were observed, respectively. When erythropoietin (Epo) was added to the combinations of IL-3 plus HPF or IL-3 plus HPF plus SCF megakaryocyte colonies were enhanced compared with the cultures without Epo. As the result of determination the ploidy distribution, more than 20% of the megakaryocytes in IL-3 plus HPF showed 32N and above ploidy, but the number of 8N and under megakaryocytes was the same as those stimulated with IL-3 alone. These results suggest that HPF stimulates both the proliferation of megakaryocyte colony-forming units and the maturation of megakaryocytes in the presence of IL-3.