Immunity against tuberculosis

The purpose of this research study is to understand how immune responses within the lung protect against respiratory infection with Mycobacterium tuberculosis, the organism that causes tuberculosis (Tb). The investigators are recruiting volunteers who have previously had a positive tuberculosis skin test (also known as a "PPD test", "tuberculin test" or "tine test"), to participate in studies of immune cells obtained from the blood and lungs. Lung cells are obtained by the procedure of bronchoalveolar lavage, which involves passing a flexible tube into the lungs and washing cells out from a small portion of one lung. Blood samples are obtained for screening evaluation and for comparison with the studies of lung cells.

Participants must be 18-50 years old. We cannot include volunteers who are current smokers, or who have asthma or other chronic lung disorders.