Airway inflammation driven by antigen-specific resident lung CD4(+) T cells in alphabeta-T cell receptor transgenic...

CD4(+) T cells are thought to play a major role in the initiation and perpetuation of T helper cell, type 2 (Th2)-like allergic airway inflammation. However, it is not clear whether activation of resident antigen-specific CD4(+) T cells is in itself sufficient to induce such a phenotype. Using ovalbumin (OVA)-specific alphabeta-T cell receptor transgenic Balb/c DO11.10 mice, we were able to test this hypothesis. Nonsensitized DO11.10 mice but not wild-type mice responded to a primary OVA aerosol with a rapid and impressive bronchoalveolar lavage (BAL) neutrophilia followed by a smaller but significant eosinophilia. Responses in DO11.10 mice were mediated by OVA-specific activation of CD4(+) T cells because in vivo depletion of CD4(+) but not CD8(+) T cells abrogated inflammatory cell influx. Cytokines measured in BAL fluid (BALF) after OVA aerosol exposure of DO11.10 mice were indicative of a T helper cell, type 1 (Th1)-like immune response. Further, neutralization of interferon gamma (IFN-gamma) with antibody enhanced eosinophil influx, suggesting that IFN-gamma production was limiting the development of a Th2 response. Despite this, an increased prevalence of cells staining for mucus was seen in the bronchial epithelium, a feature more commonly associated with a Th2-immune response. Unlike what was seen in OVA-sensitized wild-type mice, multiple OVA aerosol exposures of DO11.10 mice failed to induce airway hyperresponsiveness (AHR) to inhaled methacholine. In conclusion, in vivo stimulation of resident lung CD4(+) T cells with antigen caused lung inflammation with characteristics of both a Th1- and Th2-immune response but was insufficient to directly induce AHR.