|Budget Amount *help
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥3,000,000 (Direct Cost: ¥3,000,000)
We studied the effect of various hemopoietic growth factors and cytokines on human megakaryocytopoiesis in vitro using the serum free cultures for human megakaryocyte colonies developed by us during this research term. As a result, it was found that IL-3 or GM-CSF stimulates the growth of megakaryocyte progenitros (CFU-MK) directly without activation of accessory cells or the requirement of factors present in the serum or plasma. IL-3 and GM-CSF acted synergistically on megakaryocyte colony formation when GM-CSF was added to cultures containing suboptimal concentrations of IL-3. However, the number and the size of megakaryocyte colonies did not increase with GM-CSF when cultures were plated with an optimal dose of IL-3. Erythropoietin (Epo) or M-CSF by itself did not stimulate the growth of megakaryocyte progenitors. Epo, however, produce a significant increase in the number and size of megakaryocyte colonies in the presence of IL-3 and GM-CSF. Moreover, epo increased the ploidy values
of colony megakaryocytes. M-CSF also increased the number of megakaryocyte colonies in the presence of IL-3. Thrombopoiesis-stimulating factor, TSF distributed from Dr. McDonald stimulated megakaryocyte colony formation and enhanced the colony formation stimulated by IL-3. Other factors, including G-CSF, IL-1, IL-4, IL-5 and IL-l showed no capacity to generate or enhance megakaryocyte colony formation when added to cultures alone or in combination with varying concentrations of IL-3. These results indicate that IL-3, GM-CSF, M-CSF, Epo and TSF affect human megakaryocytopoiesis by themselves or by interacting with each other.
Pathogenesis of acquired amegakaryocytic thrombocytopenia was studied using this culture method. Since CD8_+ cells from the peripheral blood of the patient suppressed CFU-MK derived from allogeneic normal marrow cells, she was treated with cyclosporine resulting in the increase in the platelet count to the normal range. As a result, CD8_+ cell-mediated suppression of megakaryocyte progenitors is related with the pathogenesis of this disease and provide an explanation for the effectiveness of cyclosporine. Less