Inflammatory response after inhalation of bacterial endotoxin assessed by the induced sputum technique

Background-Organic dusts may cause inflammation in the airways. This study was performed to assess the usefulness of the induced sputum technique for evaluating the presence of airways inflammation using inhaled endotoxin (li popolysaccharide) as the inducer of inflammation. Methods-To characterise the inflammatory response after inhalation of endot oxin, 21 healthy subjects inhaled 40 mu g Lipopolysaccharide and were exami ned before and 24 hours after exposure. Examinations consisted of a questio nnaire for symptoms, spirometric testing, blood sampling, and collection of induced sputum using hypertonic saline. Eleven of the subjects inhaled hyp ertonic saline without endotoxin exposure as controls. Cell counts, eosinop hilic cationic protein (ECP), and myeloperoxidase (MPO) were determined in blood and sputum. Results-A significantly higher proportion of subjects reported respiratory and general symptoms after endotoxin inhalation. MPO and the number of neut rophils in the blood were higher and spirometric values were decreased afte r the lipopolysaccharide challenge. In the sputum MPO, ECP, and the numbers of neutrophils and lymphocytes were higher after the lipopolysaccharide ch allenge. No significant differences were found after the inhalation of hype rtonic saline compared with before, except for a significantly lower number of lymphocytes in the sputum. Conclusions-The results support previous studies that inhaled endotoxin cau ses an inflammation at the exposure site itself, as well as general effects . Sampling of sputum seems to be a useful tool for assessing the presence o f airways inflammation, and the inhalation of hypertonic saline used to ind uce sputum did not significantly interfere with the results found after inh alation of lipopolysaccharide.