Wu Yu-Jie, Wang Hui, Liang Jian-Hua, Miao Yi, Liu Lu, Qiu Hai-Rong, Qiao Chun, Wang Rong, Li Jian-Yong
Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, People's Republic of China.
Onco Targets Ther. 2016 Feb 18;9:797-805. doi: 10.2147/OTT.S94613. eCollection 2016.
Expression of ζ-chain-associated protein kinase 70 kDa (ZAP-70) in chronic lymphocytic leukemia (CLL) is associated with more aggressive disease and can help differentiate CLL from cases expressing mutated or unmutated immunoglobulin heavy chain variable region (IgHV) genes. However, standardizing ZAP-70 expression by flow cytometric analysis has proved unsatisfactory. The key point is that ZAP-70 is weakly expressed with a continuous expression pattern rather than a clear discrimination between positive and negative CLL cells, which means that the resulting judgment is subjective. Thus, in this study, we aimed at assessing the reliability and repeatability of ZAP-70 expression using the geometric mean fluorescence intensity (geo MFI) index method based on flow cytometry with 256-channel resolution in a series of 402 CLL patients and to compare ZAP-70 with other biological and clinical prognosticators. According to IgHV mutational status, we were able to confirm that the optimal cut-off point for the geo MFI index was 3.5 in the test set. In multivariate analyses that included the major clinical and biological prognostic markers for CLL, the prognostic impact of ZAP-70 expression appeared to have stronger discriminatory power when the geo MFI index method was applied. In addition, we found that ZAP-70-positive patients according to the geo MFI index method had shorter time to first treatment or overall survival (P=0.0002, P=0.0491). This is the first report showing that ZAP-70 expression can be evaluated by a new approach, the geo MFI index, which could be a useful prognostic method as it is more reliable, less subjective, and therefore better associated with improvement of CLL prognostication and prediction of clinical course.
70 kDa的ζ链相关蛋白激酶（ZAP-70）在慢性淋巴细胞白血病（CLL）中的表达与更具侵袭性的疾病相关，并且有助于将CLL与表达突变或未突变免疫球蛋白重链可变区（IgHV）基因的病例区分开来。然而，通过流式细胞术分析来标准化ZAP-70表达已被证明并不令人满意。关键在于ZAP-70表达较弱，呈连续表达模式，而非CLL细胞阳性与阴性之间有明确区分，这意味着所得判断具有主观性。因此，在本研究中，我们旨在采用基于具有256通道分辨率的流式细胞术的几何平均荧光强度（geo MFI）指数法，评估402例CLL患者中ZAP-70表达的可靠性和可重复性，并将ZAP-70与其他生物学和临床预后指标进行比较。根据IgHV突变状态，我们能够在测试集中确认geo MFI指数的最佳截断点为3.5。在包含CLL主要临床和生物学预后标志物的多变量分析中，应用geo MFI指数法时，ZAP-70表达的预后影响似乎具有更强的鉴别力。此外，我们发现根据geo MFI指数法判断为ZAP-70阳性的患者首次治疗时间或总生存期较短（P = 0.0002，P = 0.0491）。这是首份表明ZAP-70表达可通过一种新方法——geo MFI指数进行评估的报告，该方法可能是一种有用的预后方法，因为它更可靠、主观性更小，并因此与CLL预后改善及临床病程预测的关联性更好。
