Atopic status of an adult population with active and inactive tuberculosis

The rise in allergic disorders over the past three decades has been suggested to be related to the decrease in infectious diseases. Recently, a negative association between tuberculin responses and atopic disorders has also been reported. We planned to investigate the effect of natural exposure to Mycobacterium tuberculosis on atopic status in patients with active tuberculosis and to compare the findings with the data of patients with inactive disease. A total of 97 subjects were divided into two groups. Group 1, patients with proven active pulmonary tuberculosis (n = 66); group 2, subjects who had a history of previous tuberculous disease, with negative bacteriologic studies and no clinical and/or roentgenographic evidence of current disease (n = 31). Current history of allergic diseases was recorded by a physician with the use of a questionnaire adapted from the European Community Respiratory Health Survey (ECRHS), and skin-prick tests (SPTs) were performed using a standardized panel. Total IgE and Phadiatop were measured by the Pharmacia uniCAP system. The rate of one or more positive SPTs was significantly lower in the patients with active tuberculosis than the inactive group (15% versus 48.4%, p < 0.001). The current history of atopic diseases was 7.6% and 29% in the active and inactive tuberculosis groups, respectively (p = 0.002). The rate of positive skin tests to inhalant allergens in patients with inactive disease was higher than the rate of healthy adult Turkish people (48.4% versus 25%, p = 0.001). Geometric mean of total IgE levels were lower in patients with inactive disease than patients with active pulmonary tuberculosis (74.97 kU/L versus 106.3 kU/L, p = 0.05). The ratios of Phadiatop positivity were 21% and 38.7% in the active and inactive tuberculosis groups, respectively (p = 0.008). We found lower atopy rates in patients with active pulmonary tuberculosis than subjects with inactive disease. Although our data support the hypothesis that M. tuberculosis may prevent the development of atopic disorders by inducing the production of cytokines antagonistic to Th2 development, we believe prospective and experimental studies are needed before attributing a direct cause-effect link to this association.