Immunity to Tuberculosis. It is estimated that 1/3 of the world’s population has been infected with Mycobacterium tuberculosis (Mtb). In the majority of infected people, the immune response is able to adequately control the infection, and consequently only 5-10% will develop clinical disease during their lifetime. My long-term goal is to understand the immunological basis for protective immunity. One way we are investigating this problem is to determine why different mouse strains differ in their susceptibility to tuberculosis. We have observed that certain susceptible mouse strains are unable to efficiently recruit T cells to the lung following infection with Mtb, and this failure likely contributes to increased mortality and morbidity of susceptible mice. Therefore, we are particularly interested in the early events leading to the initiation of the pulmonary immune response following respiratory Mtb infection. This includes establishing how T cells and myeloid cells are recruited back to the lung and how these cells mediate their effector functions.