Effect of CD8+ T‐cell depletion on bronchial hyper‐responsiveness and inflammation in sensitized and allergen‐exposed Brown–Norway rats

Abstract
We examined the role of CD8+ T cells in a Brown–Norway rat model of asthma, using a monoclonal antibody to deplete CD8+ T cells. Ovalbumin (OA)‐sensitized animals were given anti‐CD8 antibody (0·5 mg/rat) intravenously 1 week prior to exposure to 1% OA aerosol and were studied 18–24 hr after aerosol exposure. Following administration of anti‐CD8 antibody, CD8+ cells were reduced to +, CD4+ and CD8+ T cells in airways. Anti‐CD8 antibody caused a further increase in allergen‐induced BHR (PP+ and CD4+ T cells in airways were not affected by anti‐CD8 treatment, the level of CD8+ T cells was significantly reduced in sensitized, saline‐exposed animals (PP+ T‐cell depletion, Th1 cytokine expression was significantly reduced (P+ T cells have a protective role in allergen‐induced BHR and eosinophilic inflammation, probably through activation of the Th1 cytokine response.