Impaired alveolar macrophage chemotaxis in patients with acute smoke inhalation

Abstract

Pulmonary infection is a leading cause of death in patients with smoke inhalation; however, few studies have evaluated the effects of inhaled smoke on the host defense mechanisms of the lung. In this study we investigated the effects of acute smoke inhalation on the random and chemotactic (stimulated unidirectional) migration of human pulmonary alveolar macrophages. Fiberoptic subsegmental pulmonary lavage was performed in 19 normal subjects (12 nonsmokers and 7 smokers) and 7 patients with smoke inhalation. After quantification of lavaged cell populations, random and chemotactic migration was measured using modified Boyden chambers. Zymosan-activated serum was used as a chemotactic stimulant. Mean +/- SE random migration was 6.2 +/- 0.8 cells per 20 microscopic fields in smoking control subjects, 5.7 +/- 0.7 in nonsmoking control subjects, and 5.2 +/- 0.7 in patients with smoke inhalation. These values are not significantly different. In contrast, the mean directed (chemotactic) migration of pulmonary alveolar macrophages was 26.5 +/- 1.9 in smoking control subjects, 22.7 +/- 3.0 in nonsmoking control subjects, and 11.4 +/- 1.4 in patients with smoke inhalation; the latter response was significantly different from that of the smoking (P less than 0.001) and nonsmoking (P less than 0.025) control subjects and the combined average of the 2 control groups (P less than 0.001. In vitro exposure of pulmonary alveolar macrophages to nontoxic doses of smoke produced similar impairment of chemotaxis. These findings may partially explain the enhanced susceptibility of patients with smoke inhalation to pulmonary infection.