The effect of plasma factor in subjects with idiopathic thrombo-cytopenic purpura on TPO-dependent megakaryocytopoiesis

进一步明确特发性血小板减少性紫癜的病理生理机制。在液相培养系统中，分析了在有或无含有抗GPIIb/IIIa自身抗体的患者血浆中，TPO依赖的脐血单个核细胞（CBMC）的巨核细胞生成。通过定量随后溶解的培养的CBMC中的血小板特异性抗原如GPIIb/IIIa来评价巨核细胞生成的程度。用建立的酶联免疫吸附试验（ELISA）系统检测血小板相关抗体或血浆抗GPIIb/IIIa自身抗体及血清TPO值。加入TPO后，在5%正常人血清存在下，CBMC的血小板特异性抗原（GPIIb/IIIa）显著增强，而在抗GPIIb/IIIa自身抗体阳性的ITP患者血清存在下，CBMC的GPIIb/IIIa显著降低，同时巨核细胞数量减少。ITP血清的这种抑制作用与TPO的浓度有关。此外，ITP血清的蛋白A亲和纯化的IgG组分显示对CBMC向巨核细胞和血小板的生长和发育的剂量依赖性抑制，这表明针对血小板特异性抗原或TPO=受体相互作用的抗体活性可以解释对TPO依赖性造血的这些抑制。在可评价的患者中，检测到患者IgG对巨核细胞生成的抑制独立于抗血小板自身抗体值或循环TPO水平。这些数据表明，可能有可检测的抗体活性，对TPO=受体相互作用，如抗TPO抗体在选定的ITP患者，这起着一定的作用，血小板减少症的发病机制，这种疾病。

To further identify pathophysiology of idiopathic thrombocytopenic purpura. TPO-depen-dent megakaryocytopoiesis of cord blood mononuclear cells(CBMC) in the exsistence or absence of patients' plasma which contains anti GPllb/llla autoantibody was analyzed under liquid-phase culture system. The degree of megakaryopoiesis was evaluated by quantitating platelet-specific antigen such as GPllb/llla in cultured CBMC subsequently solubilized. Platelet-associated or plasma anti GPllb/llla autoantibody and serum TPO values were also analyzed by established ELISA system. Add of TPO revealed extensive enhancement on platelet specific antigen (GPllb/llla) of CBMC in the presence of 5% serum from normal individuals, whereas marked decrease of GPllb/lllain supematant of solubilized CBMC was noted concomitant with a drop in number of cells morphologically identified as megakaryocytes when cultured in the existence of serum from ITP patients positive with anti GPllb/llla autoantibody. These inhibitory effcts of ITP serum were dependent on the concentration of TPO added. Furthermore, Protein A-affinity-purified lgG fraction of ITP serum showed dose-dependent suppression on the growth and development of CBMC to megakaryocyte and platelet, suggesting that an antibody activity against platelet-specific antigen or TPO=receptor interaction may account for these inhibition on TPO-dependent hematopoiesis. This suppression on megakaryocytopoiesis by patients' lgG was detected independent from antiplatelet autoantibody values or circulating TPO levels in evaluable patients. These data suggest that there may be detectable antibody activity against TPO=receptor interaction such as anti-TPO antibody in selected patients with ITP, which plays some role on the pathogenesis of thrombocytopenia of this disorder.