Rheumatoid arthritis (RA)-specific autoantibodies in patients with interstitial lung disease and absence of clinically apparent articular RA.

The purpose of this study was to identify rheumatoid arthritis (RA)-related autoantibodies in subjects with interstitial lung disease (ILD) and no articular findings of RA, supporting the hypothesis that RA-related autoimmunity may be generated in non-articular sites, such as the lung. This was a retrospective chart review utilizing clinic databases of patients with ILD to identify cases with lung disease, RA-related autoantibody positivity, and no clinical evidence of articular RA. Four patients with ILD, RF, and anti-CCP positivity and no articular findings of RA were identified. All four patients were male with a mean age at time of diagnosis of ILD of 70 years old. All had a history of smoking. Three patients died within 2 years of diagnosis of ILD and never developed articular symptoms consistent with RA; the final case met full criteria for articular RA several months after stopping immunosuppressive treatment for ILD. RF and anti-CCP can be present in smokers with ILD without clinical evidence of articular RA and in one case symptomatic ILD and autoantibody positivity preceded the development of articular RA. These findings suggest that RA-specific autoimmunity may be generated due to immunologic interactions in the lung and may be related to environmental factors such as smoking.