Chemotaxis of alveolar macrophages and neutrophils in response to microbial products derived from organic dust.

Mechanisms of chemotaxis of alveolar macrophages (AMs) and neutrophils (PMNs) in response to microbial products derived from organic dust were studied using the blindwell chemotaxis chamber technique. Seven different known etiological agents causing respiratory symptoms were used for experiments: cell extract and endotoxin from Pantoea agglomerans (synonyms: Erwinia herbicola, Enterobacter agglomerans), cell extracts from Thermoactinomyces vulgaris and Aspergillus fumigatus, protease from Bacillus thermoproteolyticus rokko and two preparations of glucans. These agents were evaluated for their ability to direct attraction of alveolar macrophages and neutrophils and stimulation of alveolar macrophages to release chemotactic factors for other alveolar macrophages and neutrophils. The microbial products were able to attract both alveolar macrophages and neutrophils directly in a dose-dependent manner, and the exposure of cultured alveolar macrophages to most agents stimulated chemotactic activity for for alveolar macrophages and neutrophils. The generation and release of this activity by alveolar macrophages may provide a mechanism for the initiation and amplification of inflammatory reactions in the lung after inhalation of organic dust. Results of these in vitro studies may be relevant to the pathogenesis of alveolitis in organic dust-induced lung diseases.