IgG IgA和IgM亚型抗环瓜氨酸肽抗体在早期类风湿关节炎中的检测及意义

Significance of antibodies of IgG, IgA and IgM subtypes antibodies against cyclic citrullinated peptide in early rheumatoid arthritis

目的检测早期类风湿关节炎（RA）患者血清中IgG、IgA和IgM亚型抗环瓜氨酸肽（CCP）抗体水平，分析3种亚型抗体在早期RA中的临床意义。方法纳入病程〈2年的RA患者87例，其他风湿病患者61例，健康对照49名。以酶联免疫吸附法（ELISA）检测血清中IgG、IgA和IgM亚型抗CCP抗体水平，并分析各抗体亚型与RA患者临床和实验室指标的关系。统计学方法采用，检验、t检验及Pearson相关分析。结果①IgG亚型和IgA亚型抗CCP抗体对诊断早期RA的敏感性分别为75．9％和67．8％，均明显优于IgM亚型抗CCP抗体（14％）（P均〈0．01）。IgG、IgA及IgM亚型抗CCP抗体对诊断RA的特异性分别为96．4％、91．8％和93．6％。②IgG和IgA亚型抗CCP抗体均与CRP（r=0．278，P=0．01；r=0．217，P=0．047）和RF（r=0．430，P=0．000；r=0．271，P=0．012）呈正相关；IgM亚型与病程（r=0．279，P=0．014）呈正相关。③IgG-IgA＋组患者病程（3．3±2．3）个月明显短于IgA-IgG＋（11／28）（9．5±8．4）个月组和IgGqgA＋（8．2±7．0）含月组（P均〈0．05）。④在IgG亚型抗CCP抗体阴性的RA患者中，仍有19．0％的患者可以检测到IgA亚型抗CCP抗体。IgG亚型和IgA亚型抗CCP抗体联合检测均阳性对早期RA诊断的敏感性为63．2％，特异性为100％，二者任一阳性的敏感性为80．5％，特异性为85．2％。结论IgG和IgA亚型抗CCP抗体对早期RA的诊断均具有较高的敏感性，并且与病情活动相关，IgA亚型对IgG型抗CCP抗体阴性的RA患者具有一定的补充诊断作用，且IgG亚型阴性而Iga亚型阳性RA患者病程更短，提示IgA亚型抗CCP抗体可能在RA的更早期阶段发挥作用。

Objective To evaluate the prevalence and clinical values of anti-cyclic citrullinated peptide （anti-CCP） antibodies of IgG, IgA and [gM subtypes in individuals with early rheumatoid arthritis （RA）. Methods IgG, IgA and IgM subtypes of anti-CCP antibodies were measured in the sera of 87 RA patients with disease duration shorter than 2 years, 61 patients with other rheumatic diseases and 49 healthy subjects. We analyzed the diagnostic value of IgG, IgA and IgM subtypes of anti-CCP antibodies and their relationship with disease duration, DAS28, ESR, CRP, and rheumatoid factor （RF）. Chi-square test, t test and Spearman＇s correlation analysis were used for statistical analysis. Results （1） The diagnostic sensitivity of IgG, and IgA subtype for early RA was 75.9% and 67.8% respectively, which was higher than IgM subtype （14%, P〈0.01 each）. The specificity of IgG, IgA and IgM subtype was 96.4% , 91.8% and 93.6% respectively. （2） IgG and IgA subtypes were correlated with CRP （r=0.278, P=0.01; r=0.217, P=0.047） and RF （r=0.430, P=0.000; r=0.271, P=0.012）, while IgM subtype was positively correlated with disease duration （r=0.279, P=0.014）. （3） Patients who had IgG＋ and [gA subtype had a shorter disease course （3.3±2.3） than those patients who had IgA- and IgG＋ （9.5±8.4） and who had IgG＋ and IgA＋ （8.2±7.0） （P〈0.05）.（4） IgA subtype was positive in 19.0% of the IgG negative patients. When e, ombining IgG, and antibodies of IgA sublypes together, the sensitivity and specificity was 63.2% and 100%, while the sensitivity and specificity was 80.5% and 85.2% when either one was positive.Conclusion Both the lgG, and IgA subtypes of anti-CCP antibodies have a good sensitivity for early RA. They are related to disease activity. Measuring IgA subtype of anti-CCP antibody in RA patients with negative IgG subtype may help to identify early RA. lgA suhtype of anti-CCP antibody may play a role in very.＂ early RA.