尿素解离法纠正2019新型冠状病毒IgM抗体检测结果假阳性的效果评价

Performance of urea-mediated dissociation in reducing false-positive of 2019-nCoV IgM test

目的:了解引起2019新型冠状病毒(2019-nCoV)免疫球蛋白M(IgM)抗体检测结果假阳性的干扰因素,探讨相应的解决方案。方法:2020年1月22日至2月15日就诊于川北医学院附属医院的不同病原体感染及相关慢性疾病患者血清样本共71份,采用胶体金免疫层析法和酶联免疫吸附法检测71例患者血清中2019-nCoV IgM抗体,其中包括6例2019-nCoV肺炎确诊患者,5例A型流感病毒IgM阳性患者,5例B型流感病毒IgM阳性患者,5例肺炎支原体IgM阳性患者,5例嗜肺军团菌IgM阳性患者和29例类风湿因子IgM阳性患者,5例高血压患者,5例糖尿病患者,6例人类免疫缺陷病毒感染患者;然后对2019-nCoV IgM抗体阳性结果进行分析,探讨造成检测结果假阳性的可能因素;再采用尿素解离试验对阳性结果的血清进行解离,以尿素最佳解离浓度进行解离后重新测定2019-nCoV IgM抗体。采用SPSS 19.0统计软件对数据进行统计学分析。结果:6例2019新型冠状病毒肺炎确诊患者和18例中高水平类风湿因子IgM阳性患者血清中2019-nCoVIgM抗体检测为阳性,其余47例受检者血清均为阴性。胶体金免疫层析法的尿素解离浓度为6 mol/L时,上述18例中高水平类风湿因子IgM阳性患者的17例的2019-nCoVIgM抗体检测为阴性,6例新型冠状病毒肺炎确诊患者血清检测仍为阳性。酶联免疫吸附法的尿素解离浓度为4 mol/L,解离时间为10 min,且亲和指数<0.46设定为阴性时,15例类风湿因子IgM阳性血清的2019-nCoVIgM抗体检测为阴性,6例2019新型冠状病毒肺炎确诊患者血清检测仍为阳性。结论:中高水平IgM型类风湿因子易造成胶体金免疫层析法和酶联免疫吸附法检测血清2019-nCoVIgM结果的假阳性,针对检测结果阳性的样本进行尿素解离将有利于降低假阳性的发生概率。

Objective To investigate the interference factors causing false-positive result of novel coronavirus IgM antibody detected by gold immunochromatography assay(GICA)and enzyme-linked immunosorbent assay(ELISA).Methods A total of 71 serum from different pathogen infections and related chronic diseases patients were collected from the Affiliated Hospital of North Sichuan Medical College from January 22,2020 to February 15,2020.GICA and ELISA were used to detect 2019-nCoV IgM in 71 serum,including 5 influenza A virus(Flu A)IgM positive serum,5 influenza B virus(Flu B)IgM positive serum,5 Mycoplasma pneumonia(MP)IgM positive serum,5 Legionella pneumophila(LP)IgM positive serum,29 rheumatoid factor(RF)IgM positive serum,5 hypertension patients serum,5 diabetes mellitus patients serum,6 human immunodeficiency virus(HIV)infection patients serum and 6 COVID-19 patients serum.The interference factors causing false positive results of the two methods were analyzed,and urea dissociation test was employed to dissociate the 2019-nCoV IgM positive serum using the best dissociation concentration.Statistical analyses were performed by SPSS,version 19.0.Results 2019-nCoV IgM was positive in 18 cases of middle-high level RF-IgM positive serum and 6 cases of 2019-nCoV-infected serum detected by two methods,and the other 47 serum were negative.When the dissociation concentration of urea was 6 mol/L,2019-nCoV IgM was negative in 17 cases of middle-high level RF-IgM positive serum and positive in 6 cases of 2019-nCoV-infected serum detected by GICA.When the urea dissociation concentration was 4 mol/L,dissociation time was 10 min and the avidity index<0.46 was set as negative,2019-nCoV IgM was negative in 15 cases of middle-high level RF-IgM positive serum and positive in 6 cases of 2019-nCoV-infected serum detected by ELISA.Conclusion The middle-high level of RF-IgM could cause false positive results of 2019-nCoV IgM detected by GICA and ELISA,and the urea dissociation test would be helpful for reducing the probability of false-positive results of 2019-nCoV IgM test.