Rheumatology Research Center and Department of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Department of Hematology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Thromb Res. 2018 Aug;168:67-77. doi: 10.1016/j.thromres.2018.06.006. Epub 2018 Jun 11.
Thrombosis is the prognostic factor with the greatest effect on survival in patients with paroxysmal nocturnal hemoglobinuria (PNH), who lack dozens of membrane surface proteins. We recently described a primary homozygous Cys89Tyr congenital nonfunctioning CD59 in humans with clinical manifestation in infancy, associated with chronic hemolysis, recurrent strokes, and relapsing peripheral demyelinating neuropathy. Here we investigated hypercoagulability mechanisms characterizing the syndrome.
Membrane attack complex (MAC) deposition (anti-SC5b-9) and free hemoglobin (colorimetric assay) were assessed. Platelet activation was identified (anti-CD61, anti-CD62P), and microparticles (MPs) of 0.5-0.9 μm, were characterized (Annexin V, anti-human GlyA, anti-CD15, anti-CD14, anti-CD61). Platelet-monocyte aggregation was assessed with FlowSight.
2/7 patients (29%) with homozygosity for Cys89Tyr and 6/12 (50%) with any of four described CD59 mutations had recurrent strokes. In plasma samples from four patients carrying identical mutations, MAC deposition was increased on RBCs (p < 0.0003), neutrophils (p < 0.009), and platelets (p < 0.0003). Free-plasma hemoglobin levels were abnormally high, up to 100 mg/dl. Patients with CD59 mutation had RBC-derived MP levels 9-fold higher than those in healthy controls (p < 0.01), and 2-2.5 fold higher than PNH patients (p < 0.09). Leukocyte-activated platelet aggregation was increased (p < 0.0062). Loss of CD59 was shown in the endothelium of these patients.
Nonfunctioning CD59 is a major risk factor for stroke and hypercoagulability. Uncontrolled hemolysis causes massive MP release and endothelial heme damage. MAC attack on unprotected endothelium and platelet activation and aggregation with leukocytes mediate additional mechanisms leading to vascular occlusion. It is suggested that CD59 loss represents a major arterial prothrombotic factor in PNH and additional diseases.
血栓形成是阵发性夜间血红蛋白尿症（PNH）患者生存预后影响最大的因素，此类患者缺乏数十种膜表面蛋白。我们最近描述了一种原发性纯合 Cys89Tyr 先天性无功能 CD59，其临床表现为婴儿期发病，伴有慢性溶血性贫血、复发性中风和复发性周围脱髓鞘神经病。在此，我们研究了该综合征的高凝机制。
评估膜攻击复合物（MAC）沉积（抗 SC5b-9）和游离血红蛋白（比色法）。鉴定血小板活化（抗 CD61、抗 CD62P），并对 0.5-0.9μm 的微颗粒（MPs）进行特征描述（ Annexin V、抗人 GlyA、抗 CD15、抗 CD14、抗 CD61）。使用 FlowSight 评估血小板-单核细胞聚集。
2/7 位（29%）纯合 Cys89Tyr 患者和 6/12 位（50%）携带四种描述的 CD59 突变之一的患者发生复发性中风。在携带相同突变的 4 位患者的血浆样本中，MAC 在 RBC 上的沉积增加（p<0.0003）、中性粒细胞（p<0.009）和血小板（p<0.0003）。游离血浆血红蛋白水平异常升高，高达 100mg/dl。与健康对照组相比，CD59 突变患者 RBC 来源的 MPs 水平高 9 倍（p<0.01），与 PNH 患者相比高 2-2.5 倍（p<0.09）。白细胞激活的血小板聚集增加（p<0.0062）。这些患者的内皮细胞中出现 CD59 缺失。
无功能 CD59 是中风和高凝的主要危险因素。失控的溶血导致大量 MPs 释放和内皮血红素损伤。MAC 对无保护内皮的攻击、血小板激活和与白细胞的聚集，介导了导致血管闭塞的其他机制。提示 CD59 缺失代表 PNH 和其他疾病中的主要动脉血栓形成因素。
