Inflammatory potential of grain dust

A comparative analysis of toxicity and inflammatory potential of spring wheat, oat, corn, and flax seed was performed. The extracts were examined by quantification of gram-negative bacterial endotoxin and protein contents, chemotaxis for purified human polymorphonuclear leukocytes, and several alveolar macrophage functions including phagocytosis, release of lactate dehydrogenase, macromolecular synthesis (protein and RNA), and interleukin-1 production. The results suggested that the extracts of all four grain dusts inhibited protein synthesis and decreased phagocytosis of alveolar macrophages at 7.5-25 mg/ml. Protein synthesis was inhibited to 40.2% of control and phagocytosis to 47.9% of control. Interleukin-1 production was stimulated, as indicated by a stimulation index range from 3.8-fold to 14.3-fold over controls. The activity of these grain dust extracts did not correlate with the endotoxin content of the samples. The data demonstrate that the extracts of all four dusts produced ill effects in rat alveolar macrophages in vitro and suggested a potential hazard to agricultural workers exposed to grain dust.