Cigarette smoking and the risk of systemic lupus erythematosus and rheumatoid arthritis.

I n this issue of the Annals, Freemer et al report an association between smoking and dsDNA autoantibody production in systemic lupus erythematosus (SLE). The authors note that exposure to tobacco smoke has previously been associated with several autoimmune diseases, including rheumatoid arthritis (RA) and SLE. In RA, cigarette smoking has been associated with rheumatoid factor (RF) positive but not RF negative disease when these two groups of subjects were evaluated separately. Likewise, smoking has been associated with anti-cyclic citrullinated antibody (anti-CCP) positive but not anti-CCP negative RA. In affected subjects, exposure to tobacco has also been associated with several measures of disease severity such as the presence of radiographic erosions, nodules, pulmonary disease, RF, and anti-CCP antibodies. A cumulative dose of exposure has been associated with a higher incidence and prevalence of RA as well as RF and anti-CCP positivity ; in studies evaluating intensity and duration separately, it appears that duration is most important. 10 Smoking has been identified as a risk factor for seropositive RA incidence, 4 and a few studies have even identified an association between cigarette smoking and RF positivity in subjects without RA, supporting a role for this exposure very early during the development of clinical disease. In this regard, it has been proposed that exposure to tobacco may trigger RF production, thus contributing to the clinical onset of RA.