Absence of relationship between tuberculin reactivity and asthmatic symptoms, level of FEV1 and bronchial hyperresponsiveness in BCG vaccinated young adults

Background: Some recent studies have suggested that bacillus Cahnette-Guerin (BCG) vaccination or mycobacterial infection early in life is inversely related to asthma. We wondered if an increase in tuberculin reactivity was inversely related to commonly used indices of asthma in a population of young adults who were BCG vaccinated at age 14. Methods: Men and women aged 20-44 years, randomly selected from the general population, were tuberculin tested with the epinephrine-Pirquet method with Norwegian-produced synthetic medium tuberculin (n=588). In addition they were interviewed using eight questions on asthma symptoms and medication. Lung function and bronchial responsiveness were also tested. Results: Altogether 95% of those studied had been BCG vaccinated at age 14 (n=558). In the 386 subjects with complete examinations, there was no relationship between a positive tuberculin reaction (greater than or equal to4 mm) and asthma symptoms or use of asthma medication. Furthermore we did not observe any relationship between a positive tuberculin reaction and the level of forced expiratory volume (FEV1) or a positive bronchial responsiveness test, assessed as the percent of predicted of FEV1 and PD20 < 2 mg methacholine, respectively. In multiple logistic regression analyses neither respiratory symptoms, level of FEV1, nor bronchial hyperresponsiveness were related to tuberculin reactivity after adjustment for age, gender and smoking habits. Conclusions: In this young adult population who were BCG vaccinated at the age of 14 no significant relationship existed between tuberculin reactivity and asthmatic symptoms, level of FEV1 or bronchial hyperresponsiveness. Our data does not support the hypothesis that BCG immunization is beneficial in reducing asthmatic symptoms and disease in young adults.