Tembhare Prashant, Ramani Manisha, Syed Keerti, Gupta Amar Das
Hematopathology and Flow Cytometry sections, Super Religare Laboratories, Mumbai, India.
Indian J Pathol Microbiol. 2010 Oct-Dec;53(4):699-703. doi: 10.4103/0377-4929.72042.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal stem cell disorder characterized by complement-mediated hemolysis due to reduced expression of glycosyl phosphatidylinositol-anchored complement deactivating proteins such as CD55 and CD59 on RBC. Flow cytometric analysis of CD55 and CD59 expression by RBC is a reliable tool for the diagnosis of PNH.
Detection and quantification of PNH clone and comparison of the relative role of CD55 and CD59 expression by RBC in the diagnosis of PNH.
Flow cytometric analysis of RBC was performed in blood samples of 239 patients by direct immunofluorescence using monoclonal anti-CD55 and anti-CD59 antibodies. CD55 and CD59 expressions by RBC were compared in 54 cases in which PNH clones were detected.
Out of 54 cases, 85% and 72% revealed CD59 and CD55 negative populations, respectively. Various combinations of type II and III erythrocytes could be identified in all cases having CD59 deficient RBC. In contrast, distinct populations of CD55-deficient RBC were seen in only 33% cases. In the remaining (67%) cases, CD55 negative RBC caused sloping of the ascending limb of the histogram resulting in difficulties in interpretation. Fifteen percent cases had false CD55-deficient RBC and in 23% cases anti-CD55 antibody failed to identify PNH clones which were detected by CD59.
CD59 is a better marker for the diagnosis of PNH. Although CD55 negativity supported the diagnosis of PNH in cases with CD59-deficient RBC, its role as an independent diagnostic marker for PNH is questionable due to its lower sensitivity and specificity.
阵发性睡眠性血红蛋白尿（PNH）是一种获得性克隆性干细胞疾病，其特征是由于红细胞（RBC）上糖基磷脂酰肌醇锚定的补体失活蛋白（如CD55和CD59）表达降低而导致补体介导的溶血。通过流式细胞术分析RBC上CD55和CD59的表达是诊断PNH的可靠工具。
检测和定量PNH克隆，并比较RBC上CD55和CD59表达在PNH诊断中的相对作用。
使用单克隆抗CD55和抗CD59抗体，通过直接免疫荧光法对239例患者的血样进行RBC的流式细胞术分析。在检测到PNH克隆的54例患者中比较RBC上CD55和CD59的表达。
在54例患者中，分别有85%和72%显示CD59和CD55阴性群体。在所有CD59缺陷RBC的病例中均可识别出II型和III型红细胞的各种组合。相比之下，仅在33%的病例中可见明显的CD55缺陷RBC群体。在其余（67%）的病例中，CD55阴性RBC导致直方图上升支倾斜，从而难以解释。15%的病例存在假CD55缺陷RBC，23%的病例中抗CD55抗体未能识别出通过CD59检测到的PNH克隆。
CD59是诊断PNH的更好标志物。虽然CD55阴性在CD59缺陷RBC的病例中支持PNH的诊断，但其作为PNH独立诊断标志物的作用因其较低的敏感性和特异性而受到质疑。
