循环心肌肌钙蛋白Ⅰ自身抗体的检测及临床意义

目的 了解急性心肌梗死(AMI)和心肌炎患者循环内抗心肌肌钙蛋白Ⅰ(cTnI)自身抗体的阳性率,促进临床实验室正确认识和了解这种特异性自身抗体对cTnI检测的负性干扰.方法 建立检测cTnI自身抗体的ELISA方法,在121例AMI和24例心肌炎患者血清中进行cTnI自身抗体的筛查;采用Western Blot对cTnl自身抗体阳性血清进一步验证;通过回收试验分析cTnI自身抗体对cTnI检测干扰的特异性.结果 121例AMI患者中有10.74%(13/121)cTnI自身抗体阳性,24例心肌炎患者中有8.3%(2/24)cTnl自身抗体阳性.将cTnI-C融合蛋白(cTnI终浓度为0.625-100ug/L)加入1例cTnI自身抗体阳性的血清中进行回收试验,各浓度cTnI均出现不同程度的低回收,并呈正相关(Spearman相关系数=0.943,P=0.005);而加入正常人血清中的cTnI回收率则没有明显的改变(Spearman相关系数=0.377,P=0.461).当加入终浓度为20ug/L的cTnI时,13份cTnI自身抗体阳性的AMI患者血清中有5份回收率<80%.结论 心肌损伤患者循环中存在cTnI自身抗体并非罕见,所产生的负性干扰足以使cTnI的检测结果失真,应在临床实验室引起高度重视.

Detection of circulating cardiac troponin I autoantibodies and its clinical significance

Objective To detect the positivity of circulating autoantibodies against cardiac troponin Ⅰ (cTnI) in acute myocardial infarction (AMI) and myocarditis patients and investigate the interference of the antibodies with the detection of cTnI. Methods cTnI ELISA was established for assessment of sera obtained from 121 patients with AMI, 24 with myocarditis and 210 healthy subjects. Binding specificity of cTnI antibody from positive sera by ELISA was confirmed with Western Blot. The recovery of cTnl studies was employed to evaluating the effects of cTnl autoantibodies on cTnI immunoassays. Results Thirteen of the 121 AMI patients (10.74%) and 2 of the 24 myocarditis patients (8.3%) had positive anti-cTnI antibodyas compared with none in the healthy subjects. The recovery of cTnI by adding cTnI-C fusion proteincorresponding to final cTnI concentration of 0.625-100 ug/L to sample with anti-cTnI antibody wasinhibited significantly (Spearman correlation coefficient r=0.943, P=0.005 ). There was no significantchange of recovery of cTnl when adding it to a normal sera(Spearman correlation coefficient r=0.377,P=0.461). When cTnI-C complex corresponding to 20 ug/L cTnI was added, 5 of the 15 sera with anti-cTnIantibody were found with the inhibition of recovery (<80%). Conclusions Autoantibodies against cTnIwere increasing in patients with AMI and myocarditis, yet it appears that these autoantibodies could interferenegatively with the cTnI immunoassay. Thus, it should be paid more attention to cTnI immunoassays.