Significance of antibodies of IgG, IgA and IgM subtypes antibodies against cyclic citrullinated peptide in early rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective To evaluate the prevalence and clinical values of anti-cyclic citrullinated peptide (anti-CCP) antibodies of IgG,IgA and IgM 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 IgA 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 combining IgG,and antibodies of IgA subtypes 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 IgG,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.IgA subtype of anti-CCP antibody may play a role in very early RA.