Bodrova V V, Khaspekova S G, Shustova O N, Tsvetaeva N V, Mazurov A V
Chazov National Medical Research Center of Cardiology, Moscow, Russia.
National Medical Research Center of Hematology, Moscow, Russia.
Biomed Khim. 2025 Sep;71(4):288-299. doi: 10.18097/PBMCR1596.
Immune thrombocytopenia (ITP) is one of the most common causes of decreased platelet count. Bleeding is the main clinical symptom of ITP; although its severity correlates with the depth of thrombocytopenia, it may also depend on changes in the functional activity of platelets. In this study we have compared platelet functional activity in healthy volunteers (HV) and in ITP patients, as well as in groups of ITP patients with different levels of bleeding. The study included 65 HV and 84 ITP patients. Platelet activity was assessed by flow cytometry. Platelets were activated with thrombin receptor activating peptide (TRAP) or ADP, and the exposure of activation markers, activated form of glycoprotein (GP) IIb-IIIa and alpha-granule membrane protein P-selectin, was determined on their surface by measuring the binding of PAC-1 and CD62P antibodies, respectively. Platelet-associated IgG (PA-IgG, an indicator of the level of antiplatelet autoantibodies), the percentage of "young" reticular platelets (RP, %) and platelet light scatter (an indicator of their size) were also assessed using flow cytofluorimetry. Platelet binding of PAC-1 (and, to a lesser extent, CD62P binding) was lower in ITP patients than in HV. In ITP patients, PAC-1 binding inversely correlated with the PA-IgG content. In contrast to HV, in ITP patients, PAC-1 and CD62P binding did not directly correlate with the platelet size and RP, %. In ITP patients with severe bleeding, the platelet count was lower, PAC-1 and CD62P binding was reduced and PA-IgG and RP, % levels were increased. Thus, a decrease in the content of activation markers on the platelet surface was registered in ITP patients; it was more pronounced in patients with severe bleeding. It is suggested that the cause of this decrease may be due to the effect of autoantibodies (PA-IgG) on platelets, and in particular on GP IIb-IIIa.
免疫性血小板减少症（ITP）是血小板计数降低的最常见原因之一。出血是ITP的主要临床症状；尽管其严重程度与血小板减少的程度相关，但也可能取决于血小板功能活性的变化。在本研究中，我们比较了健康志愿者（HV）、ITP患者以及不同出血水平的ITP患者组的血小板功能活性。该研究纳入了65名HV和84名ITP患者。通过流式细胞术评估血小板活性。用凝血酶受体激活肽（TRAP）或ADP激活血小板，并分别通过测量PAC-1和CD62P抗体的结合来测定其表面激活标志物（糖蛋白（GP）IIb-IIIa的激活形式和α-颗粒膜蛋白P-选择素）的暴露情况。还使用流式细胞荧光术评估血小板相关IgG（PA-IgG，抗血小板自身抗体水平的指标）、“年轻”网状血小板（RP，%）的百分比以及血小板光散射（其大小的指标）。ITP患者中PAC-1的血小板结合（以及在较小程度上CD62P的结合）低于HV。在ITP患者中，PAC-1结合与PA-IgG含量呈负相关。与HV不同，在ITP患者中，PAC-1和CD62P结合与血小板大小和RP，%没有直接相关性。在严重出血的ITP患者中，血小板计数较低，PAC-1和CD62P结合减少，PA-IgG和RP，%水平升高。因此，在ITP患者中记录到血小板表面激活标志物含量降低；在严重出血的患者中更为明显。提示这种降低的原因可能是自身抗体（PA-IgG）对血小板，特别是对GP IIb-IIIa的作用。
