Role of CD8 (+) T Cells in Airway Inflammation and Hyperresponsiveness

Rha, Yeong Ho; Choi, Sun Hee

Abstract

PURPOSE
Allergic asthma is a complex syndrome of reactions within the airways characterized by bronchoconstriction, airway inflammation and airway hyperresponsiveness (AHR). There is an emerging body of knowledge defining the role of CD8 (+) T cells in the pathogenesis of allergic asthma. The role of CD8 (+) T cells in the development of allergic airway disease is still controversial. The purpose of this study was to investigate the role of CD8 (+) T cells during the induction of allergen-induced AHR and airway inflammation. METHODS: Mice were sensitized to OVA by i.p. injection on day 1, 14 and then challenged by OVA inhalation on days 24, 25, 26. Anti-CD8 antibody was administered to sensitized mice by i.v. injection 2h before second sensitization and first airway challenge. In vivo airway responsiveness was measured by whole body plethysmography (Penh) to inhaled methacholine (MCh) on day 28. Lung eosinophilia, bronchoalveolar lavage fluid (BALF) cytokine levels were also assessed. RESULTS: Sensitized and challenged mice showed significant airway eosinophilia and heightened responsiveness to methacholine when compared with nonsensitized animals. Administration of anti-CD8 antibody prevented both development of AHR as well as bronchoalveolar lavage fluid eosinophilia. Anti-CD8 antibody abolished peribronchial and perivascular infiltration of inflammatory cells. Treatment with anti-CD8 antibody also resulted in supression of IL-5 production in bronchoalveolar lavage fluid. CONCLUSION: These results indicate that CD8 (+) T cell may have a potential role in the development of allergic airway inflammation and development of allergen-induced airway responses.