Increased IgA anti‐citrullinated protein antibodies in the periodontal inflammatory exudate of healthy individuals compared to rheumatoid arthritis patients

AIM: To assess rheumatoid arthritis (RA)‐associated autoantibodies in the gingivocrevicular fluid (GCF) of RA patients and healthy controls with or without periodontal disease, as chronic mucosal inflammation in periodontal disease is hypothesized to contribute to the formation of these autoantibodies. MATERIALS AND METHODS: Anti‐citrullinated protein antibodies (ACPA), rheumatoid factor (RF), and their IgA isotypes were assessed in the serum and GCF of RA patients (n = 72) and healthy controls (HC, n = 151). The presence and levels of these antibodies were studied in relation to interleukin (IL)‐8 and periodontal disease. RESULTS: In contrast to the HC, the levels of ACPA and RF in the serum and GCF of the RA patients were strongly correlated (p < .0001). The HC with high levels of IgA‐ACPA (n = 27) also had significantly higher levels of total IgG, total IgA, and IL‐8 in the GCF than the HC with low levels of IgA‐ACPA in the GCF (n = 124). Periodontal inflammation and smoking were seen more frequently in the group with high levels of IgA‐ACPA compared to the group with low IgA‐ACPA. CONCLUSION: The IgA‐ACPA in the GCF of HC may be associated with periodontal inflammation and smoking, and could be involved in the progression to RA.