Does atopy affect the radiological extent of pulmonary tuberculosis?

Th1 cytokines, IL-2 and IFN-gamma , have critical importance in the CD4 cell driven antimycobacterial activity. Th2 type immune response is a characteristic feature of atopic disorders. Th1 and Th2 cells have been reported to negatively cross-regulate each other in vitro and in experimental animals. Our aim in the present study is to determine whether the atopy affects radiological extent of pulmonary tuberculosis (TB) and disease severity.

A total of 82 male patients with pulmonary TB were prospectively enrolled in the study between March 2005 and March 2006. All patients were evaluated for atopic symptoms and TB related systemic symptoms. Radiological dissemination was scored and cavitation was noted. The skin prick test (SPT) was performed and serum total IgE level was measured.

The SPTs were positive in 28 of 82 (34.1 %) patients. There was no distinction between SPT-positive and negative patients in terms of pulmonary cavitation and radiological dissemination. The median IgE level of moderate-severe radiologically disseminated TB patients was significantly higher than that of mild radiologically disseminated TB patients (130 IU/ml vs. 58 IU/ml). Cavitary TB patients had also significantly higher median IgE levels (78 IU/ml vs. 46 IU/ml) (p < 0.05)

This study suggests that SPT-positivity and atopic respiratory phenotype do not affect the formation of cavitation, radiological dissemination and systemic symptoms of pulmonary TB. The high level of IgE in patients with cavitary and radiologically disseminated TB may be a consequence of a dysregulated immune response to infection or reflect disease activity.