Determination of anti-cyclic citrullinated peptide antibodies in the sera of patients with liver diseases.

OBJECTIVE To determine the frequency of anti-cyclic citrullinated peptide (anti-CCP) antibodies in patients with HCV infection, primary biliary cirrhosis (PBC) and type-I autoimmune hepatitis (AIH) to assess the specificity of anti-CCP antibodies. METHODS Rheumatoid factor (RF) and anti-CCP antibodies were measured in the sera from patients with HCV infection (n=45), PBC (n=73), AIH (n=55) and rheumatoid arthritis (n=48), and also from the sera of healthy subjects (n=23). Anti-CCP antibodies were measured using a second generation enzyme-linked immunosorbent assay (ELISA). RESULTS No sera with elevated anti-CCP were found in the patients with HCV infection. Two PBC patients (2.7%) and six AIH patients (10.5%) had anti-CCP antibodies. The seropositivity for anti-CCP in these autoimmune disease patients was associated with a high frequency of RA association [PBC; 100% (2/2), AIH; 86.4% (5/6)]. CONCLUSIONS Although anti-CCP antibodies may be present in patients with autoimmune liver diseases, almost seropositive patients had concomitant RA. As a result, the measurement of anti-CCP antibodies may therefore be helpful for accurately diagnosing RA in patients with these liver diseases.