Our laboratory's main interest is the development of cell-mediated immunity within the human lung. In particular, we are primarily investigating how pulmonary immune responses provide protection against Mycobacterium tuberculosis (Mtb), the bacteria that causes tuberculosis (TB).
The current TB vaccine, known as BCG, is given to newborns in most of the world as an injection between layers of the skin. Although BCG does protect against development of widely disseminated TB disease in young children, it is not effective at preventing pulmonary TB in adults. Nevertheless, most otherwise healthy individuals who are infected with Mtb do not develop active disease, but instead develop specific immunity that controls the organism and is likely to provide protection from further respiratory exposures to Mtb. Individuals with immunity to Mtb can be identified by positive TB skin tests (or "PPD tests") and by specific blood tests (such as the "QuantiFERON" test). Immunity that develops in response to respiratory infection with Mtb may be more effective than that induced by BCG vaccination in preventing pulmonary TB because organism-specific immune cells display the property of "homing"; that is, they preferentially return to the tissue sites at they were first exposed to a pathogen.
Our studies involve collecting lung cells from healthy volunteers who have evidence of prior Mtb infection for use in laboratory studies of immune responses to Mtb. We also recruit healthy non-smokers without Mtb infection to serve as control subjects. Additional studies also involve the use of animal models of TB vaccination and infection, which are used to help confirm the significance of the findings from our studies of human subjects.