Giannini S, Mezzasoma A M, Guglielmini G, Rossi R, Falcinelli E, Gresele P
Division of Internal and Cardiovascular Medicine, Department of Internal Medicine, University of Perugia, Perugia, Italy.
Cytometry B Clin Cytom. 2008 May;74(3):194-9. doi: 10.1002/cyto.b.20396.
Acquired Glanzmann's thrombasthenia (aGT) is a rare hemorrhagic disorder caused by autoantibodies, alloantibodies, or paraproteins directed against platelet GPIIb/IIIa. Its diagnosis requires several laboratory assays and mixing tests, which are complex and time consuming. We describe here a new case of aGT and compare different tests for the detection of GPIIb/IIIa-blocking autoantibodies.
A previously healthy 27-year-old male developed severe mucocutaneous bleeding, despite a normal platelet count, associated with non Hodgkin lymphoma.
Blood clotting tests were normal. Bleeding time and PFA-100 were unmeasurable. Platelet aggregation was absent in response to all agonists except ristocetin. Platelet adhesion to collagen at high shear was impaired. Platelet granular content and release was normal. Flow cytometry showed normal binding of some anti-GPIIb/IIIa antibodies (SZ21 and SAP), and decreased binding of others (P2, SZ22, A2A 9/6). Binding of PAC-1, against activated GPIIb/IIIa, and of fibrinogen, was absent. In mixing tests, patient's serum inhibited aggregation, adhesion, and PAC-1 and A2A9/6 binding to control platelets. The patient's antibody, purified by affinity chromatography, recognized purified GPIIb by western blotting. Isolated patient's IgG inhibited platelet aggregation and A2A 9/6 binding by flow cytometry.
Flow cytometry is especially useful for the diagnosis of aGT, being the only test able to characterize both the functional effect and the molecular target of the patient's autoantibody.
获得性血小板无力症（aGT）是一种罕见的出血性疾病，由针对血小板糖蛋白IIb/IIIa的自身抗体、同种抗体或副蛋白引起。其诊断需要多种实验室检测和混合试验，这些检测复杂且耗时。我们在此描述一例aGT新病例，并比较检测GPIIb/IIIa阻断性自身抗体的不同试验。
一名既往健康的27岁男性，尽管血小板计数正常，但出现严重的黏膜皮肤出血，伴有非霍奇金淋巴瘤。
凝血试验正常。出血时间和PFA-100无法测量。除瑞斯托霉素外，对所有激动剂的血小板聚集均缺失。高剪切力下血小板与胶原的黏附受损。血小板颗粒内容物和释放正常。流式细胞术显示一些抗GPIIb/IIIa抗体（SZ21和SAP）结合正常，而其他抗体（P2、SZ22、A2A 9/6）结合减少。针对活化GPIIb/IIIa的PAC-1和纤维蛋白原的结合缺失。在混合试验中，患者血清抑制对照血小板的聚集、黏附以及PAC-1和A2A9/6的结合。通过亲和层析纯化的患者抗体经蛋白质印迹法可识别纯化的GPIIb。分离的患者IgG通过流式细胞术抑制血小板聚集和A2A 9/6结合。
流式细胞术对aGT的诊断特别有用，是唯一能够同时表征患者自身抗体的功能效应和分子靶点的检测方法。
