血清抗PLA2R抗体和肾小球IgG4联合检测在膜性肾病诊断中的应用

Serum anti-phospolipase A2 receptor antibodies and glomerular IgG4 in the diagnosis of membranous nephropathy

目的 探讨膜性肾病（MN）患者血清抗磷脂酶A2受体（PLA2R）抗体与肾小球IgG4的相关性,评价血清抗PLA2R抗体和肾小球IgG亚型检测在膜性肾病诊断中的价值.方法 病例来自2011年10月至2014年4月北京协和医院收治的MN患者,按照临床诊断分为特发性膜性肾病（IMN）组,膜型狼疮肾炎组（MLN）和继发性膜性肾病（SMN）组.间接免疫荧光法检测患者血清抗PLA2R抗体水平.免疫荧光法检测患者肾小球IgG亚型表达.采用受试者工作特征（ROC）曲线分析血清抗PLA2R抗体和肾小球IgG4的诊断价值.结果 IMN组血清抗PLA2R抗体阳性率69.5％（41/59）;MLN组阳性率4.8％（1/21）.IMN组中血清抗PLA2R抗体和肾小球IgG4共阳性者35例,血清抗PLA2R抗体阳性而肾小球IgG4阴性者6例,血清抗PLA2R抗体阴性而肾小球IgG4阳性者17例,血清抗PLA2R抗体和肾小球IgG4共阴性者1例.血清抗PLA2R抗体诊断IMN的灵敏度69.5％,特异度95.2％;肾小球IgG4亚型诊断IMN的灵敏度89.8％,特异度52.3％;两者共阳性的灵敏度59.3％,特异度100.0％.6例乙型肝炎病毒（HBV）相关性膜性肾病患者中4例血清抗PLA2R抗体阳性,3例干燥综合征（pSS）相关性膜性肾病和3例肿瘤相关性膜性肾病患者各有1例血清抗PLA2R抗体呈阳性.结论 IMN患者血清抗PLA2R抗体阳性率高,SMN患者PLA2R抗体阳性率随病因而异;血清抗PLA2R抗体联合肾小球IgG4亚型检测有助于膜性肾病病因的诊断和鉴别诊断.

Objective To discuss the relationship between serum anti-Phosphalipase A2 receptor （PLA2R） antibodies and glomerular IgG4 subclass in patients with membranous nephropathy and evaluate the diagnostic value of the two markers.Methods Patients diagnosed as membranous nephropathy from October 2011 to April 2014 in Peking Union Medical College Hospital were included and divided into IMN and SMN groups accoding to their clinical diagnosis.Serum anti-PLA2R antibodies and glomerular IgG subclasses were both detected by indirect immunofluorescence assay.Receiver operator characteristic curves were used to evaluate the diagnostic efficiency of anti-PLA2R antibodies and glomerular IgG4.Results Prevalence of serum anti-PLA2R antibodies of IMN patients was 69.5％ （41/59）; prevalence of MLN patients was 4.8％ （1/21）.Within the IMN group,thirty-five patients showed positive results of both serum anti-PLA2R antibodies and glomerular IgG4; Six patients were positive for serum anti-PLA2R antibodies but negative for glomerular IgG4; Seventeen patients were positive for glomerular IgG4 but negative for serum anti-PLA2R antibodies; one patient was negative for both tests.The sensitivity of serum anti-PLA2R antibody was 69.5％ and the specificity was 95.2％; the sensitivity of glomerular IgG4 was 89.8％ and the specificity was 52.3％.The sensitivity of the combined marker consisting of serum anti-PLA2R antibody and glomerular IgG4 was 59.3％ and the specificity was 100％.Four out of the six patients secondary to HBV infection,one out of the three patients secondary to Sj（o）gren syndrome,one out of the three patients secondary to malignant tumor showed positive results of serum anti-PLA2R antibodies.Conclusions Serum antiPLA2R antibodies were of high prevalence among IMN patients; the prevalence among SMN patients varied with etiologies.Results of serum anti-PLA2R antibodies and glomerular IgG4 were helpful to rule out secondary etiologies in the diagnosis of membrnous nephropathy.