Smoking and risk of treatment-induced neutralizing antibodies to interferon β-1a

Background: Neutralizing antibodies (NAbs) to interferon beta (IFN beta) products that develop during treatment are associated with a loss of clinical efficacy. Objectives: The aim of this study was to investigate the influence of smoking habits on the risk of developing NAbs to IFN beta, in the treatment of multiple sclerosis (MS). Methods: This report is based on 695 MS patients treated with IFN beta-1a, included in two Swedish case-control studies that collected information on smoking habits. Using logistic regression, the development of NAbs to IFN beta-1a among current smokers was compared with that of non-smokers, by calculating the odds ratio (OR) with a 95% confidence interval (CI). Results: Current smokers showed an increased risk of developing NAbs to IFN beta-1a, compared with non- smokers (OR 1.9; 95% CI 1.3-2.8; p = 0.002). There were no gender differences. We observed no association between past smoking and the risk of developing NAbs to IFN beta-1a. Conclusions: The finding that current smokers have an increased risk of developing NAbs to IFN beta-1a has implications, both for the practical care and the treatment of MS; it also provides an interesting perspective of the lungs as an immune-reactive organ, reacting upon irritation.