[Possible contribution of lung macrophage to airway hyperreactivity]

To elucidate the possible contribution of lung macrophage to airway hyperreactivity, we studied the effect of canine pulmonary alveolar macrophages (PAM) stimulated with anti-dinitrophenyl (DNP) IgE antibody and DNP-human serum albumin on airway smooth muscle and epithelial functions in vitro. IgE-stimulated PAM increased the contractile responses of bronchial segments to electrical field stimulation and the short-circuit current of cultured tracheal epithelium, the former effect being abolished in the presence of the thromboxane A2 receptor antagonist and the latter inhibited by the leukotriene antagonist and the Cl transport blocker. These results suggest that PAM may increase the parasympathetic contraction and Cl secretion in the airway through IgE-dependent release of thromboxane A2 and leukotriene, respectively.