Juvenile idiopathic arthritis (JIA), a chronic inflammatory systemic disease of autoimmune background, causes progressive destruction of the joints. To establish the diagnosis of JIA at the onset of the disease is very difficult, because clinical symptoms are not clear and IgM rheumatoid factor (IgM-RF), contrary to adult rheumatoid arthritis (RA), is found rarely. Anti-cyclic citrullinated peptide (CCP) antibodies are considered to be a specific marker of RA in adults. However, limited reports concern anti-CCP antibodies value in children with JIA and the researches opinions are not clear.
Objective To access the prevalence, diagnostic and clinical significance of anti-CCP antibodies in children with JIA.
Methods Sera of 96 JIA children were examined for anti-CCP, IgM-RF and anti-nuclear (ANA) antibody levels. Anti-CCP positivity was correlated with the disease characteristics. The control group consisted of 50 healthy children.
Results For anti-CCP antibodies, sensitivity was 41.6% and specificity 100%. Anti-CCP autoantibodies were present in both IgM-RF-positive and negative sera in all subtypes of JIA onset. Among children with early stage of JIA (disease duration <6 months) 40.7% were anti-CCP positive. Anti-CCP levels correlated positively with high disease activity. All healthy children were anti-CCP negative. The sensitivity of IgM-RF and ANA were significantly lower (14.5% and 8.3%, respectively).
Conclusion Anti-CCP antibodies are present in sera of JIA children, also at the early stage of the disease, in various subtypes of JIA. Anti-CCP antibodies are present in both IgM-RF-positive and IgM-RF-negative sera. Moreover, anti-CCP antibodies are sensitive markers of disease activity.