Histopathology of Neutrophil Infiltrate in the Walls of Asthmatic Airways

Nova Southeastern University, Davie, Florida, USA

Background: Bronchial asthma is an inflammatory disorder of the airways involving an array of inflammatory cells and multiple mediators. Attempts have been made to define different asthma syndromes on the basis of preponderance of specific inflammatory cells found in bronchial infiltrates. Objective: To make a quantitative assessment, particularly of neutrophil (poly-morpho-nuclear cell, PMN) infiltration and marginated cells in the bronchial vessels in the fast onset syndrome asthma (<1>h). Methods: Lung tissue was randomly sampled at autopsy from 19 cases of asthma, and 21 control subjects (death due to non-respiratory disease). Entire cross sections of bronchi were paraffin embedded, H&E stained and with light microscope, equipped with 60X objective, neutrophil number was assessed by cell count in the lamina propria, 100-300 um depth from basement membrane (BM). The counts were expressed as # of PMNs /mm of BM length. Results: In fast onset asthma (<1>h) subjects, the average number of PMNs was ten folds higher (15.26 ± 14.52 STDV) when compared to control subjects (1.14 ± 2.01 STDV). From examined cases we found that high neutrophil infiltration was not seen in all cases of the fast onset asthma, however, the higher neutrophil infiltration closely correlated with the histopathological damage of the examined airways. Conclusion: The neutrophil pool of both tissue emigrated and blood vessel marginated cells indicate a likely role in the pathogenesis of asthma affecting the bronchial basement membrane denudation and epithelial loss, exposing the airway surface to further inflammatory process. Grants: NSU Faculty Research Grant.