Significance of antibodies of IgG, IgA and IgM isotypes against peptidylarginine deiminase 4 in early rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective To evaluate the prevalence and clinical significance of IgG,IgA and IgM isotypes of anti-peptidylarginine deiminase 4 (anti-PAD4) antibodies in early rheumatoid arthritis (RA).Methods IgG,IgA and IgM isotypes of anti-PAD4 antibodies were measured in the sera of 88 RA patients with disease duration less than 2 years,62 patients with other rheumatic diseases and 57 healthy subjects.The diagnostic performance of IgG,IgA and IgM isotypes of anti-PAD4 antibodies and their relationship with disease duration,DAS28,ESR,CRP,anti-CCP antibodies and rheumatoid factor (RF) were evaluated.Data analysis were performed using t test,U test and Spearman's association analysis.Results ① The sensitivities of IgG,IgA,and IgM isotypes for early RA were 28.41％,36.36％ and 9.09％ respectively.The specificities of IgG,IgA and IgM isotypes were 94.12％,93.28％ and 95.80％ respectively.② IgA isotype was positively correlated with age (r=0.234,P=0.028),DAS28 (r=0.309,P=0.007),ESR (r=0.382,P=0.000) and CRP (r=0.291,P=0.008),while negatively correlated with disease duration (r=-0.295,P=0.006).③ IgA isotype was positively correlated with IgG isotype (r=0.451,P＜0.01).In the IgG negative patients,the positivity of IgA isotype was 29％(18/63),which indicated that the IgA isotype might be helpful in diagnosing RA in IgG isotype negative patients.Conclusion Anti-PAD4 antibodies can be detected in early RA,primarily with IgA and IgG isotypes.IgA isotype has negative correlation with disease duration,indicating that IgA isotype of anti-PAD4 antibody may play a role in the very early stage RA.