[Role of IgG antibody to galactose-deficient IgA1 in children with IgA nephropathy].

Objective: In order to learn the serum level of galactose-deficient IgA1 (GdIgA1), IgG antibody to galactose-deficient IgA1(GdIgA1-IgG) and the clinical role of them in IgA nephropathy(IgAN) children. Method: We compared blood levels of GdIgA1, GdIgA1-IgG in 33 children with IgAN, 38 children with other renal disease (including focal segmental glomerular nephritis, minimal change disease, Alport syndrome and thin basement membrane nephropathy) as disease controls, 35 healthy children as normal controls with enzyme-linked immunosorbent assay(ELISA). Twenty-four-hour urine protein content and Lee's pathological classification were collected in IgAN cases. The difference among the three groups were examined by analysis of variance. The specificity and sensitivity of GdIgA1, GdIgA1-IgG to IgA nephropathy were evaluated by ROC curve.The correlations were analyzed by correlation analysis among GdIgA1, GdIgA1-IgG and urine protein content and pathological classification . All statistical analyses were performed by SPSS 18.0. P value of <0.05 was considered statistically significant. Result: The levels of GdIgA1 and GdIgA1-IgG significantly elevated in children with IgAN compared to disease controls and normal controls. GdIgA1(mg/L): 1.728±0.456, 1.123±0.461, 1.410±0.905 (F=15.04, P<0.001); GdIgA1-IgG(g/L): 1.299±0.499, 1.111±0.549, 0.628±0.142 (F=76.96, P<0.001). Area under the curve of ROC of GdIgA1 between IgAN and normal controls was 0.765, with specificity 0.943 and sensitivity 0.697, while the area under the curve of GdIgA1-IgG was 0.969, with specificity 0.971 and sensitivity 0.939.The blood level of GdIgA1-IgG was mildly correlated with both 24-hour urine protein(r=0.364, ) and renal pathological grading(r=0.392) in children with IgAN. Conclusion: The levels of GdIgA1 and GdIgA1-IgG significantly elevated in children with IgAN compared to disease controls and normal controls. GdIgA1-IgG had higher sensitivity in distinguishing IgAN from normal controls, GdIgA1-IgG was mildly correlated with 24-hour urine protein volume and pathological grading in children with IgAN.目的： 探讨儿童IgA肾病中血糖基化异常免疫球蛋白A1(GdIgA1)、抗GdIgA1抗体IgG(GdIgA1－IgG)水平及其在IgA肾病临床应用中的价值。 方法： 选取首都医科大学附属北京儿童医院肾病科2013年8月至2015年12月确诊原发IgA肾病儿童33例作为研究组，男∶女＝2∶1，年龄(9.7±2.9)岁，选取本院同期病理诊断非IgA肾病儿童38例(包括局灶性节段性肾小球肾炎、微小病变性肾病、Alport综合征、薄基底膜肾病)为疾病对照组，选取正常儿童35例作为正常对照组。采用酶联免疫吸附法测定三组血GdIgA1、GdIgA1－IgG水平，应用方差分析分析各组间GdIgA1、GdIgA1－IgG水平的差异，并进一步做ROC曲线分析两项指标在疾病诊断中的特异度和敏感度；收集IgA肾病患者临床蛋白尿水平及病理Lee氏分级，通过相关性分析，分析GdIgA1、GdIgA1－IgG水平与蛋白尿及肾脏病理分级间的相关性。统计软件采用SPSS 18.0，以P<0.05为差异有统计学意义。 结果： (1)GdIgA1(mg/L)在IgA肾病组、疾病对照组和正常对照组中分别为1.728±0.456、1.123±0.461 、1.410±0.905(F＝15.04，P<0.001)；GdIgA1－IgG(g/L)在三组中分别为1.299±0.499 、1.111±0.549、0.628±0.142(F＝76.96，P<0.001)；(2)IgA肾病组与正常对照组间，GdIgA1的ROC曲线下面积为0.765，其特异度为0.943，敏感度为0.697；GdIgA1－IgG的ROC曲线下面积为0.969，其特异度为0.971，敏感度为0.939。但在IgA肾病组与疾病对照组间两指标的诊断特异度和敏感度下降。血GdIgA1－IgG水平与尿蛋白定量(r＝0.364)及病理Lee氏分级(r＝0.392)呈低度相关。 结论： IgA肾病儿童血GdIgA1、GdIgA1－IgG水平较正常对照组升高，IgA肾病与正常对照组间，GdIgA1、GdIgA1－IgG均有较高诊断特异度，而敏感度GdIgA1－IgG更高。血GdIgA1－IgG水平与尿蛋白定量及肾脏病理Lee氏分级呈低度相关。.