| Abstract: | Non-adherent bone marrow cells of a bled rabbit were cultured in plasma clot media containing auto-serum, alpha-medium, erythropoietin (Ep) and spleen extract from irradiated rats. The preparations were cloted on a cover glass, fixed and stained by Giemsa or hemoglobin staining method after 3 or 5 days in culture, and the number of erythroid colony was counted as reported elsewhere. In the present study, first, it was elucidated that the optimal numbers of innoculating cells were among 0.6 approximately 1.2 x 10(4) cells per well for the erythroid colony formation. Second, this colony formation was slightly stimulated by the experimental media which contained heat treated extract at 40 degree or 50 degree C for 30 minutes. Contrary this, the extract treated at 70 degree C for 30 minutes lost completely its stimulating activity of the colony formation, suggesting that the effective substances might be protein in the extract. Third, an inhibitory factory might be present in the dialysate of the crude spleen extract, because the number of erythroid colonies decreased in a dose response manner by the dialysate. The residue of inner dialysate, however, certainly contained the colony stimulating factors (s). The crude extract was separated into five fractions (F1 approximately F5) by ammonium sulfate. F1, which was precipitated with 40% ammonium sulfate, had the highest activity for the colony formation. Fetuin also showed appreciable effect on the erythroid colony formation. |
