Objective To investigate the clinical utility of anti-dsDNA antibody in the diagnosis of systemic lupus erythematosus (SLE).Methods Total and high affinity anti-dsDNA antibodies of 431 serum samples were measured by total and high affinity anti-dsDNA antibody EIA kits.Modified SLE disease activity index (M-SLEDAI) was scored for each SLE patients at the time of serum collection.The agreements between total and high affinity anti-dsDNA EIA tests and the correlation of anti-dsDNA antibody levels with disease activity and clinical manifestations were analyzed.Statistical analysis was performed using x2 test,Spearman correlation,Mann Whitney U test & Fisher exact,Student t test.Results ① The overall agreement between total and high affinity anti-dsDNA antibodies was 93.3％,and the total agreement of SLE patients was 89.6％.Twenty-two out of 23 (95.7％) SLE patients with positive total anti-dsDNA antibody but high affinity antidsDNA antibody were inactive with the M-SLEDAI score less than 4.Four patients with other autoimmune diseases had positive total anti-dsDNA antibody but negative on high affinity anti-dsDNA antibodies.② The total and high affinity anti-dsDNA antibody levels were significantly positively correlated with disease activity (M-SLEDAI) and negatively correlated with serum C3 and C4 levels (P＜0.01).③ The ratio of high affinity to total anti-dsDNA antibody was significantly higher in patients with M-SLEDAI ≥4 or with active kidney damage (P＜0.01).Conclusion Both total and high affinity anti-dsDNA antibodies are significantly correlated with SLE disease activity and kidney damage.However,the high affinity anti-dsDNA antibody may be more specific for active SLE and helpful in the differential diagnosis with other autoimmune diseases.High affinity anti-dsDNA antibody is more valuable in monitoring SLE disease activity status,especially on kidney damage,compared to total anti-dsDNA antibodies.%目的 比较不同亲和力的抗dsDNA抗体在SLE诊断中的临床意义.方法 用ELISA检测431份血清中总抗dsDNA抗体(包括高亲和力和低亲和力抗dsDNA抗体)与高亲和力抗dsDNA抗体水平.收集标本时,评价SLE患者的M-SLEDAI得分.采用x2检验、Spearman相关、Mann Whitney U检验和Fisher exact方法、Student t检验.结果 ①所有血清总抗dsDNA抗体与高亲和力抗dsDNA抗体的总的一致性为93.3％; SLE患者总抗dsDNA抗体与高亲和力抗dsDNA抗体一致性为89.6％,有23例SLE患者总抗dsDNA抗体阳性而高亲和力抗dsDNA抗体阴性,其中22例(占95.7％)的M-SLEDAI评分＜4分;4例其他CTD患者血清总抗dsDNA抗体阳性,而高亲和力抗dsDNA抗体阴性.②SLE患者血清总抗dsDNA抗体(r=0.57,P＜0.01)以及高亲和力抗dsDNA抗体水平(r=0.59,P＜0.01)均与M-SLEDAI评分呈正相关,与血清中补体C3(r=-0.50,P＜0.01;r=-0.54,P＜0.01)和C4(r=-0.50,P＜0.01;r=-0.50,P＜0.01)水平呈相关.③M-SLEDAI评分≥4分的患者血清中高亲和力占总抗dsDNA抗体的比例显著高于M-SLEDAI评分＜4分的患者.伴肾脏损害患者高亲和力抗dsDNA抗体所占比例显著高于不伴肾脏损害的患者.结论 血清中总抗dsDNA抗体和高亲和力抗dsDNA抗体水平均与SLE病情活动性以及肾脏损害相关,但是高亲和力抗dsDNA抗体对活动性SLE患者更具有特异性,也更有助于SLE与其他自身免疫病鉴别.检测血清中高亲和力抗dsDNA抗体比检测总抗dsDNA抗体更能客观了解SLE的受累状况.
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