Hézard Nathalie, Simon Gérard, Macé Catherine, Jallu Vincent, Kaplan Cécile, Nguyen Philippe
Laboratoire d'Hématologie, CHU Robert Debré, Reims, France.
Transfusion. 2008 Mar;48(3):513-8. doi: 10.1111/j.1537-2995.2007.01556.x. Epub 2007 Dec 7.
The diagnosis of immune thrombocytopenic purpura (ITP) is a diagnosis of exclusion, as stated by international guidelines. Nevertheless, the assessment of platelet (PLT) antibodies has been reported as helpful for the diagnosis and the follow-up of ITP patients. PLT antibodies are detected by highly specialized assays, such as monoclonal antibody-specific immobilization of PLT antigen (MAIPA) test. Flow cytometry for PLT-associated immunoglobulin G (PAIgG) detection has been described more recently. This study was meant to evaluate the utility of flow cytometry to screen accurately patients needing further MAIPA testing.
PAIgG, PAIgM, and PAIgA were determined in 107 consecutive patients and in 147 healthy controls in parallel. MAIPA testing was performed in all patients. The accuracy of flow cytometry was assessed with a receiver operating characteristics (ROC) curve analysis versus MAIPA.
MAIPA assay found PLT-specific IgG in 27 patients (25%). The ROC curve analysis showed that no false-negative result in flow cytometry was obtained for a mean fluorescence intensity (MFI) cutoff of 0.2. With this cutoff, PAIgG were positive in 61 patients (57%). In this series, MAIPA was unnecessary in 42 percent of patients (corresponding to true-negative results). When MAIPA was positive, PAIgM values ranged from 0.1 to 1.0, and PAIgA from 0.1 to 2.
Flow cytometry for PAIgG assessment may be used to accurately decide whether or not MAIPA must be subsequently performed. In this series, MAIPA was unnecessary in 42 percent of patients. Moreover, PAIgM results suggested that its determination combined with PAIgG may be of interest in ITP investigation.
正如国际指南所述，免疫性血小板减少性紫癜（ITP）的诊断是一种排除性诊断。然而，据报道血小板（PLT）抗体评估有助于ITP患者的诊断和随访。PLT抗体通过高度专业化的检测方法进行检测，如血小板抗原单克隆抗体特异性固定（MAIPA）试验。最近也描述了用于检测血小板相关免疫球蛋白G（PAIgG）的流式细胞术。本研究旨在评估流式细胞术准确筛选需要进一步进行MAIPA检测的患者的效用。
连续对107例患者和147例健康对照同时测定PAIgG、PAIgM和PAIgA。所有患者均进行MAIPA检测。通过与MAIPA的受试者操作特征（ROC）曲线分析评估流式细胞术的准确性。
MAIPA检测在27例患者（25%）中发现了血小板特异性IgG。ROC曲线分析表明，对于平均荧光强度（MFI）临界值为0.2，流式细胞术未获得假阴性结果。以此临界值，61例患者（57%）的PAIgG呈阳性。在本系列中，42%的患者无需进行MAIPA检测（对应真阴性结果）。当MAIPA呈阳性时，PAIgM值范围为0.1至1.0，PAIgA范围为0.1至2。
用于PAIgG评估的流式细胞术可用于准确判定是否随后必须进行MAIPA检测。在本系列中，42%的患者无需进行MAIPA检测。此外，PAIgM结果表明，其与PAIgG联合检测可能对ITP研究有意义。
