Kato T, Horie K, Hagiwara T, Maeda E, Tsumura H, Ohashi H, Miyazaki H
Pharmaceutical Research Laboratory, Kirin Brewery Co., Ltd., Gunma, Japan.
Exp Hematol. 1996 Aug;24(10):1209-14.
The recently cloned factor thrombopoietin (TPO) has been shown to exhibit megakaryocyte colony-stimulating activity in vitro. In this investigation, to further evaluate the action of TPO on megakaryocyte progenitor cells (colony-forming units-megakaryocyte [CFU-MK]), GpIIb/IIIa+ and GpIIb/IIIa- populations of CFU-MK were prepared from rat bone marrow cells based on their reactivity with P55 antibody, a monoclonal antibody against rat GpIIb/IIIa, and their responsiveness to recombinant human TPO (rhTPO) and recombinant rat interleukin-3 (rrIL-3) was examined using a megakaryocyte colony-forming assay (Meg-CSA). rhTPO supported only megakaryocyte colony growth from both fractions in a dose-dependent fashion. The mean colony size observed with the GpIIb/IIIa+ population was smaller than that seen with the GpIIb/IIIa- population. With the optimal concentration of either rhTPO or rrIL-3, similar numbers of megakaryocyte colonies were formed from the GpIIb/IIIa+ population previously shown to be highly enriched for CFU-MK. In contrast, the maximum number of megakaryocyte colonies from the GpIIb/IIIa- population stimulated by rhTPO was only 24.2% of that achieved with rrIL-3. Morphologic analysis of rhTPO-promoted megakaryocyte colonies from the GpIIb/IIIa+ population showed that the average colony size was smaller but that the mean diameter of individual megakaryocytes was larger than in megakaryocyte colonies promoted with rrIL-3. rhTPO plus rrIL-3, each at suboptimal concentrations, had an additive effect on proliferation of CFU-MK in the GpIIb/IIIa+ fraction, whereas rhTPO plus murine IL-6 or murine granulocyte-macrophage colony-stimulating factor (mG-M-CSF) modestly but significantly reduced megakaryocyte colony growth. These results indicate that TPO preferentially acts on GpIIb/IIIa+ late CFU-MK with lower proliferative capacity and interacts with some other cytokines in CFU-MK development.
最近克隆出的血小板生成素（TPO）已被证明在体外具有巨核细胞集落刺激活性。在本研究中，为了进一步评估TPO对巨核细胞祖细胞（巨核细胞集落形成单位[CFU-MK]）的作用，基于CFU-MK与P55抗体（一种抗大鼠GpIIb/IIIa的单克隆抗体）的反应性，从大鼠骨髓细胞中制备了CFU-MK的GpIIb/IIIa+和GpIIb/IIIa-群体，并使用巨核细胞集落形成试验（Meg-CSA）检测了它们对重组人TPO（rhTPO）和重组大鼠白细胞介素-3（rrIL-3）的反应性。rhTPO以剂量依赖的方式仅支持两个部分的巨核细胞集落生长。观察到GpIIb/IIIa+群体的平均集落大小小于GpIIb/IIIa-群体的。使用rhTPO或rrIL-3的最佳浓度时，先前显示富含CFU-MK的GpIIb/IIIa+群体形成的巨核细胞集落数量相似。相比之下，rhTPO刺激的GpIIb/IIIa-群体的巨核细胞集落最大数量仅为rrIL-3所达到数量的24.2%。对来自GpIIb/IIIa+群体的rhTPO促进的巨核细胞集落进行形态学分析表明，平均集落大小较小，但单个巨核细胞的平均直径大于rrIL-3促进的巨核细胞集落。rhTPO加rrIL-3，各自处于次优浓度时，对GpIIb/IIIa+部分的CFU-MK增殖具有相加作用，而rhTPO加小鼠IL-6或小鼠粒细胞-巨噬细胞集落刺激因子（mG-M-CSF）则适度但显著降低巨核细胞集落生长。这些结果表明，TPO优先作用于增殖能力较低的GpIIb/IIIa+晚期CFU-MK，并在CFU-MK发育过程中与其他一些细胞因子相互作用。
