Prevalence of IgA class antibodies to cyclic citrullinated peptide in patients with inflammatory bowel disease (IBD).

Determine the prevalence of anti-CCP isotype IgA and its relation to peripheral arthritis in patients with inflammatory bowel disease (IBD). In a population-based cohort of 654 patients with a definitive diagnosis of IBD, 521 patients were clinically examined by a rheumatologist 6 years after IBD diagnosis Blood serum samples of 416 of these patients were available and analyzed. Antibodies against cyclic citrullinated peptides anti-CCP IgA were determined in the serum samples by an immunofluoresence technique ELiA TM. Among the 416 IBD patients, 5 had a positive IgA class anti-CCP, giving a prevalence of 1.2%. Only four anti-CCP IgA-negative patients had a positive rheumatoid factor IgM, compared to two out of five anti-CCP IgA-positive IBD patients (10.2% versus 40.0%; p = 0.002). There were four patients with rheumatoid arthritis, two in each patient population (0.5% versus 40.0%; p = 0.0007). Four of the five anti-CCP IgA-positive IBD patients had arthritis, two with rheumatoid arthritis, and two with other arthritis. In this first study on the prevalence of IgA anti-CCP antibodies in IBD patients, we demonstrate a low prevalence, but these antibodies are associated with arthritis and positive IgM rheumatoid factor in IBD patients.