Personal Factors Affecting Therapeutic Responses to BCG Vaccination in Asthmatics

PURPOSE Bacille Calmette-Guérin (BCG) vaccination has been reported to be an effective treatment for asthma in several animal models. This study investigated whether the response to BCG treatment in asthma depends on subject clinical characteristics. METHODS Stable asthma patients were vaccinated with BCG. One month later, alterations in pulmonary function after vaccination and their relationships with subject clinical characteristics were determined. RESULTS Of 149 patients with asthma, 54 (36.2%) showed a good or fair response to BCG. The ΔFEV1 after vaccination was significantly related to age (r=-0.348, P<0.001), peripheral blood eosinophil counts (r=0.315, P<0.001) and baseline FEV1, expressed as % personal best value (r=-0.474, P<0.001), but not to FEV1 % predicted value (r=-0.066, P>0.05). A good/fair response was highly prevalent in atopic females compared with atopic males, especially among those aged ≤50 years (90.9% vs. 40.0%, P=0.024). Age (P<0.001, odds ratios (OR)=0.92, confidence interval (CI)=0.88-0.96) and atopy (P<0.01, OR=4.95, CI=1.70-14.44) were significant predictors for a good/fair response in females. However, blood eosinophil counts (P<0.05, OR=1.18, CI=1.01-1.39) and FEV1 % best (P<0.001, OR=0.86, CI=0.79-0.94), but not age or atopy, were significant predictors in males. Approximately three-quarters of the males were smokers. CONCLUSIONS The therapeutic effect of BCG in asthma may differ according to patient clinical characteristics. The greatest benefit occurred in young atopic females. Asthma activity indices, such as eosinophilia and FEV1 % best, were more predictive of a good/fair response in males; this may have been related to cigarette smoking.