Severe immune thrombocytopenia secondary to Waldenström's macroglobulinemia with anti-GPIb/IX monoclonal IgM antibody.
Severe immune thrombocytopenia secondary to Waldenström's macroglobulinemia with anti-GPIb/IX monoclonal IgM antibody.
复制标题
使用抗 GPIb/IX 单克隆 IgM 抗体继发于瓦尔登斯特伦巨球蛋白血症的严重免疫性血小板减少症。
DOI：
10.1007/s00277-013-1857-3
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发表时间：
2014
期刊：
影响因子：
3.5
通讯作者：
Yasukawa M.
中科院分区：
文献类型：
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作者：
Yamanouchi J;Hato T;Niiya T;Azuma T;Yasukawa M.
尊敬的编辑，瓦尔登斯特伦巨球蛋白血症（WM）是一种淋巴组织增生性疾病，其特征是小淋巴细胞和浆细胞样细胞浸润到骨髓中，并伴有血清IgM单克隆丙种球蛋白病[1，2]。副蛋白可能包括自身抗体，导致5-16%的WM患者出现自身免疫并发症[3，4]。少数报告提到了WM相关的免疫性血小板减少症（ITP）的机制，血小板相关IgM（PA-IgM）和IgG（PA-IgG）已被证明是可能的原因[4，5]。然而，是否单克隆IgM在WM诱导ITP知之甚少。我们在此报告一位WM合并血小板减少症的病人，其IgM可识别血小板表面膜上的GPIb/IX，并抑制GPIb介导的血小板聚集。一位68岁男性因广泛性紫癜及大量血尿而转介至我科。他的血细胞计数显示血红蛋白为5.3 g/dL，白色细胞为1.4× 109/L，血小板为6.0× 109/L。血小板大小正常。血清IgM、IgG和伊加水平分别为1，980、1，470和55 mg/dL。免疫电泳显示几乎所有的IgM都是单克隆的。骨髓有核细胞包括44.2%的淋巴样细胞和0.6%的浆细胞样细胞，其对CD 10、CD 19、CD 20、CD 38和SmIg-κ呈阳性，但对CD 5和CD 23呈阴性。他被诊断为WM，并接受环磷酰胺治疗。由于怀疑WM诱发ITP，我们检测了他的IgM对血小板的影响。流式细胞术检测显示他的IgM与正常血小板结合，而IgG不与正常血小板结合。为了鉴定IgM识别的血小板抗原，我们采用了PakAuto测定。该测定使我们能够表征血小板结合IG的抗原。然而，我们未能获得IG洗脱患者的血小板，因为非常低的血小板计数。然后将患者血清与正常血小板一起孵育，洗脱血小板结合的IG，以从患者的全血清中浓缩血小板特异性IG。此外，我们使用碱性磷酸酶缀合的山羊抗人IgG和IgM（BioFX，Owings米尔斯，MD，美国）作为二抗以分别检测IgG和IgM。我们证实，当采用PakAuto测定试剂盒中的阳性和阴性对照时，这些抗体产生有效和特异性的信号。使用这种改进的测定法，我们发现洗脱的IgM与固定的血小板膜GPIb/IX结合，但不与GPIIb/IIIa或GPIa/IIa结合（图1）。洗脱的IgG不与任何类型的GP结合。
Dear Editor, Waldenström's macroglobulinemia (WM) is a lymphoproliferative disorder characterized by infiltration of small lymphocytes and plasmacytoid cells into bone marrow and by serum IgM monoclonal gammopathy [1, 2]. The paraprotein may include an autoantibody resulting in autoimmune complications in 5–16% of patients with WM [3, 4]. A few reports have referred to the mechanism of immune thrombocytopenia (ITP) associated with WM, and platelet-associated IgM (PA-IgM) and IgG (PA-IgG) have been shown to be a possible cause [4, 5]. However, whether monoclonal IgM in WM induces ITP is poorly understood. We report here a patient with WM and thrombocytopenia whose IgM recognized GPIb/IX on the surface membrane of platelets and inhibited GPIb-mediated platelet aggregation. A 68-year-old male was referred to our department because of extensive purpura and macrohematuria. His blood counts revealed 5.3 g/dL hemoglobin, 1.4× 109/L white blood cells, and 6.0× 109/L platelets. Platelet size was normal. Serum levels of IgM, IgG, and IgA were 1,980, 1,470, and 55 mg/dL, respectively. Immunoelectrophoresis revealed that almost all IgM was monoclonal. Bone marrow-nucleated cells comprised 44.2% lymphoid cells and 0.6% plasmacytoid cells, which were positive for CD10, CD19, CD20, CD38, and SmIg-κ, but negative for CD5 and CD23. He was diagnosed as having WM and treated with cyclophosphamide. He was refractory to platelet transfusion and died of brain hemorrhage 1 week later.Because WM-induced ITP was suspected, we examined the effect of his IgM on platelets. Flow cytometry assay showed that his IgM bound to normal platelets whereas his IgG did not. To identify the platelet antigen recognized by IgM, we employed a PakAuto assay. This assay enables us to characterize the antigen of platelet-bound Ig. However, we failed to obtain Ig eluted from patient's platelets because of very low platelet count. Then the patient's serum was incubated with normal platelets and the platelet-bound Ig was eluted in order to concentrate plateletspecific Ig from the patient's whole serum. Furthermore, we employed alkaline phosphatase-conjugated goat anti-human IgG and IgM (BioFX, Owings Mills, MD, USA) as secondary antibody to detect IgG and IgM separately. We confirmed that these antibodies produced efficient and specific signals when the positive and negative controls in the PakAuto assay kit were employed. Using this modified assay, we found that the eluted IgM bound to the immobilized platelet membrane GPIb/IX, but not to GPIIb/IIIa or GPIa/IIa (Fig. 1). The eluted IgG did not bind to any type of GP.