C5 contents and neutrophil chemotactic activities in bronchiolar and alveolar regions

Abstract

To clarify the localization and mechanism of neutrophil infiltration in the lower respiratory tract, we measured neutrophil number, neutrophil chemotactic factor (NCF) activity and content of C5 in bronchial lavage (BL) fluid and bronchoalveolar lavage (BAL) fluid. Numbers of neutrophils, NCF activity and C5 content were higher in the BL fluid from normal volunteers (NV) and control patients (CP) than those in the BAL fluid from the same subjects. The NCF activity in the BL fluid was inhibited approximately 40% by anti-C5 antiserum, and correlated with C5 content in the BL fluid. In the BAL fluids of patients with chronic airway diseases (CAD) and patients with idiopathic interstitial pneumonia (IIP), neutrophil number, NCF activity and C5 content were increased compared to those in BAL fluid from NV or CP. These results indicated that neutrophils are predominant in the bronchial region compared to the alveolar region, and that C5-derived NCF play important roles in the accumulation of neutrophils in the bronchial region. Also C5-derived NCF are thought to be related to, at least, a part of the neutrophil infiltration in the respiratory tract of patients with CAD and IIP.