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

目的：进一步探讨特发性血小板减少性紫癜的病理生理学。在液相培养系统下，分析了患者血浆中含有抗GPllb/llla自身抗体的情况下，脐带血单个核细胞（CBMC） tpo依赖性巨核细胞生成的情况。通过定量测定培养后溶解的CBMC中血小板特异性抗原（如GPllb/llla）来评估巨核生成程度。建立ELISA系统，分析血小板相关或血浆抗GPllb/llla自身抗体和血清TPO值。添加TPO后，在5%正常人血清中，CBMC的血小板特异性抗原（GPllb/llla）显著增强，而在抗GPllb/llla自身抗体阳性的ITP患者血清中培养时，CBMC的GPllb/lllain上补液显著减少，形态学上鉴定为巨核细胞的细胞数量下降。ITP血清的这些抑制作用依赖于添加TPO的浓度。此外，ITP血清中蛋白a亲和纯化的lgG部分对巨核细胞和血小板的CBMC生长和发育显示出剂量依赖性抑制，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能解释了这些对TPO依赖性造血的抑制。在可评估的患者中，检测到lgG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。这些数据提示，在部分ITP患者中可能存在抗TPO=受体相互作用的抗体活性，如抗TPO抗体，这在该病血小板减少的发病机制中起一定作用。

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.