Autoantibodies for gastrointestinal organ-specific autoimmune diseases in rheumatoid arthritis patients and their relatives.

Background: Clustering of autoimmune diseases is common and may be due to genetic background and exposition to environmental triggers.

Objective: The aim is to carry out a laboratory and clinical study of the prevalence of gastrointestinal organ-specific autoantibodies in rheumatoid arthritis (RA) patients and their relatives.

Methods: Serum samples of 156 RA patients, 200 relatives, and 100 healthy controls were studied for anti-smooth muscle antibody (ASMA), anti-mitochondrial (AMA), anti-parietal cell (APCA), anti-liver-kidney microsome (LKM), and anti-endomysium antibodies (IgA-EmA) by indirect immunofluorescence.

Results: A total of eight out of the 156 (5.1%) RA patients were positive for the autoantibodies (ASMA = 1; AMA = 2, APCA = 5). In the relative group, 12/200 (6%) had at least one positive autoantibody (ASMA = 1; AMA = 2, APCA = 7, IgA-EmA = 2). In the control group, two out of the 100 (2%) healthy controls were positive (ASMA = 1, APCA = 1). No statistical difference was found between RA patients, their relatives, and controls in relation to the frequency of autoantibodies evaluated.

Conclusions: Although RA patients and their relatives have positivity of AMA, ASMA, and APCA without statistical difference in relation to healthy individuals, the findings may be of value for adequate clinical approach of these subjects.