Mast cells can amplify airway reactivity and features of chronic inflammation in an asthma model in mice

The importance of mast cells in the development of the allergen-induced air way hyperreactivity and inflammation associated with asthma remains controv ersial. Vile found that genetically mast cell-deficient WBB6F(1)-W/W-nu mic e that were sensitized to ovalbumin (OVA) without adjuvant, then challenged repetitively with antigen intranasally: exhibited much weaker responses in terms of bronchial hyperreactivity to aerosolized methacholine, lung tissu e eosinophil infiltration, and numbers of proliferating cells within the ai rway epithelium than did identically treated WBB6F(1)-+/+ normal mice. Howe ver, W/W-nu mice that had undergone selective reconstitution of tissue mast cells with in vitro-derived mast cells of congenic +/+ mouse origin exhibi ted airway responses that were very similar to those of the +/+ mice. By co ntrast, W/W-nu mice that were sensitized with OVA emulsified in alum and ch allenged with aerosolized OVA exhibited levels of airway hyperreactivity an d lung tissue eosinophil infiltration that were similar to those of the cor responding +/+ mice. Nevertheless, these W/W-nu mice exhibited significantl y fewer proliferating cells within the airway epithelium than did identical ly treated +/+ mice. These results show that, depending on the "asthma mode l" investigated, mast cells can either have a critical role in, or not be e ssential for, multiple features of allergic airway responses in mice.