Effect of inhaled endotoxin on induced sputum in normal, atopic, and atopic asthmatic subjects

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Abstract
BACKGROUND Inhalation of lipopolysaccharide (LPS) causes an inflammatory response in the lungs. To explore this response, inflammatory indices were measured in induced sputum from atopic asthmatic patients and compared with atopic and non-atopic subjects after inhalation of LPS. METHODS The effects of inhaled LPS (60 μg) or placebo (0.9% saline) were examined in a randomised, double blind, crossover trial in 11 non-atopic normal subjects, seven atopic, non-asthmatic individuals, and eight atopic, asthmatic patients. Sputum was induced by inhalation of 3.5% saline before the test inhalation and again at six hours and 24 hours. Spirometry (forced expiratory volume in one second (FEV1), forced vital capacity (FVC)), heart rate, blood pressure, and temperature were recorded before challenge and at intervals until eight hours, and at 24 hours after challenge. RESULTS There was no change in cardiovascular parameters or spirometry with either exposure in any group. In the asthmatic patients only, inhalation of LPS caused a rise in temperature, with a peak of 0.6°C at seven hours, which was significantly higher than following placebo inhalation (p6 cells/ml after LPS; median 0.2 × 106 cells/ml after placebo, pCONCLUSIONS Inhalation of LPS causes a neutrophilic inflammation with increases in IL–8 in both normal and asthmatic subjects.