Kuter D J, Gminski D M, Rosenberg R D
Department of Medicine, Massachusetts General Hospital, Boston.
Blood. 1992 Feb 1;79(3):619-26.
Using a rat bone marrow culture system, the effect of transforming growth factor beta 1 (TGF beta 1) on megakaryocyte growth and endoreduplication has been studied. Purified human platelet TGF beta 1 inhibited the number of megakaryocytes that appeared in culture at a half-maximal concentration of 0.66 +/- 0.21 ng/mL and inhibited megakaryocyte endoreduplication at a half-maximal concentration of 0.14 +/- 0.08 ng/mL. Under identical conditions, growth of erythroid precursors was half-maximally inhibited at a concentration of 0.125 ng/mL while myeloid growth was not inhibited at concentrations of TGF beta 1 up to 25 ng/mL. These profound inhibitory effects on megakaryocyte growth and endomitosis suggested that TGF beta might play a role in megakaryocytopoiesis. Therefore, we explored the effect of TGF beta in three different experimental situations by using a neutralizing antibody to TGF beta: (1) Serum but not plasma was found to inhibit the number and ploidy of megakaryocytes that grew in vitro. This inhibitory activity was completely neutralized by antibody to TGF beta or on treatment with dithiothreitol. (2) Plasma from thrombocytotic rats was observed to decrease megakaryocyte ploidy on culture but this effect was not prevented by the addition of antibody to TGF beta. (3) Plasma from thrombocytopenic but not normal rats increased megakaryocyte ploidy on culture. Addition of antibody to TGF beta did not alter these results. Therefore, TGF beta is a potent inhibitor of the number and ploidy of megakaryocytes and accounts for all the inhibition seen when megakaryocytes are cultured in serum. However, the differences in effect on megakaryocyte growth that we observe between normal, thrombocytopenic, and thrombocytotic plasmas are not due to variations in the amount of TGF beta. Furthermore, our results show that release of TGF beta from megakaryocytes during culture does not act as an autocrine regulator of megakaryocyte ploidy in vitro.
利用大鼠骨髓培养系统，研究了转化生长因子β1（TGFβ1）对巨核细胞生长和核内复制的影响。纯化的人血小板TGFβ1抑制培养中出现的巨核细胞数量，其半数最大抑制浓度为0.66±0.21 ng/mL，抑制巨核细胞核内复制的半数最大抑制浓度为0.14±0.08 ng/mL。在相同条件下，红系前体细胞的生长在浓度为0.125 ng/mL时受到半数最大抑制，而在TGFβ1浓度高达25 ng/mL时，髓系生长未受抑制。这些对巨核细胞生长和核内有丝分裂的显著抑制作用表明，TGFβ可能在巨核细胞生成中发挥作用。因此，我们通过使用TGFβ中和抗体在三种不同的实验情况下探索了TGFβ的作用：（1）发现血清而非血浆可抑制体外生长的巨核细胞数量和倍性。这种抑制活性可被TGFβ抗体完全中和或经二硫苏糖醇处理后消除。（2）观察到血小板增多症大鼠的血浆可降低培养时巨核细胞的倍性，但添加TGFβ抗体并不能阻止这种作用。（3）血小板减少症大鼠而非正常大鼠的血浆可增加培养时巨核细胞的倍性。添加TGFβ抗体并未改变这些结果。因此，TGFβ是巨核细胞数量和倍性的有效抑制剂，并且解释了在血清中培养巨核细胞时所见的所有抑制作用。然而，我们观察到的正常、血小板减少症和血小板增多症血浆对巨核细胞生长的作用差异并非由于TGFβ含量的变化。此外，我们的结果表明，培养过程中巨核细胞释放的TGFβ在体外并非巨核细胞倍性的自分泌调节因子。
