Immunity to tuberculosis: a delicate balance between protection and pathology

The currently used tuberculosis (TB) vaccine (Bacillus Calmette-Guérin) does not consistently prevent pulmonary infection. Novel vaccine strategies require an in-depth characterization of the cellular and molecular mechanisms of antituberculous protection. This review summarizes relevant data obtained in animal models of TB infection. In mycobacterial infections, immunologically mediated protection is intrinsically associated with tissue damage in the form of granuloma formation. The implications of this finding for future vaccine design and evaluation are discussed.