Cigarette smoking impairs human pulmonary immunity to mycobacterium tuberculosis.

Rationale: Cigarette smoking is linked to important aspects of tuberculosis, such as susceptibility to infection, disease reactivation, mortality, transmission, and persistent infectiousness. The mechanistic basis for this remains poorly understood.Objectives: To compare the functional impairment seen in human alveolar macrophages (AM) from nonsmokers, smokers, and ex-smokers after infection with Mycobacterium tuberculosis (Mtb).Methods: AM were acquired at bronchoscopy, and number and viability from smoking donors were compared with nonsmoking donors. AM were challenged in vitro with Mtb and intracellular bacterial viability was measured. Cytokine secretion was measured 24 hours postinfection by ELISA. Previously we determined the frequency of CD4+FoxP3+ T cells in the presence or absence of allogeneic AM, and data were reanalyzed to separate the patient subjects according to smoking status.Measurements and Main Results: There were significantly more AM from smokers compared with nonsmokers or ex-smokers...