THE ROLE OF T-LYMPHOCYTES IN PULMONARY MICROBIAL DEFENSE-MECHANISMS

Understanding how lung immunity develops against pulmonary pathogens s hould lead to more rational approaches in vaccine design and to the us e of recombinant cytokines in lung disease. T lymphocytes are central to the development of effective immune responses; therefore, understan ding how lung immunity develops will require a study of how and where T cells respond to respiratory antigens. Our laboratory has helped def ine the phenotype and function of lung dendritic cells, which likely p lay an essential role in stimulating naive T cells to respond to antig ens. We found that both interstitial and alveolar macrophages can regu late the function of these cells, the former to enhance activity, the latter to suppress. In addition, we developed a murine pulmonary infec tion model using the fungus, Cryptococcus neoformans, in which T-cell- mediated immunity is essential for effective host clearance of the org anism. The role of T cells in this model is to recruit and activate ef fector cells to resolve the lung infection; both CD4 and CD8 T-cell su bsets are required for optimal effector cell recruitment. These studie s are summarized as examples of current approaches to understanding pu lmonary immunity.