γδ T Cells Regulate the Early Inflammatory Response toBordetella pertussisInfection in the Murine Respiratory Tract

Abstract

The role of γδ T cells in the regulation of pulmonary inflammation followingBordetella pertussisinfection was investigated. Using a well-characterized murine aerosol challenge model, inflammatory events in mice with targeted disruption of the T-cell receptor δ-chain gene (γδ TCR^−/−mice) were compared with those in wild-type animals. Early following challenge withB. pertussis, γδ TCR^−/−mice exhibited greater pulmonary inflammation, as measured by intra-alveolar albumin leakage and lesion histomorphometry, yet had lower contemporaneous bacterial lung loads. The larger numbers of neutrophils and macrophages and the greater concentration of the neutrophil marker myeloperoxidase in bronchoalveolar lavage fluid from γδ TCR^−/−mice at this time suggested that differences in lung injury were mediated through increased leukocyte trafficking into infected alveoli. Furthermore, flow cytometric analysis found the pattern of recruitment of natural killer (NK) and NK receptor⁺T cells into airspaces differed between the two mouse types over the same time period. Taken together, these findings suggest a regulatory influence for γδ T cells over the early pulmonary inflammatory response to bacterial infection. The absence of γδ T cells also influenced the subsequent adaptive immune response to specific bacterial components, as evidenced by a shift from a Th1 to a Th2 type response against theB. pertussisvirulence factor filamentous hemagglutinin in γδ TCR^−/−mice. The findings are relevant to the study of conditions such as neonatalB. pertussisinfection and acute respiratory distress syndrome where γδ T cell dysfunction has been implicated in the inflammatory process.