Inhalation of 200 μg of lipopolysaccharide (LPS) in normal subjects and 20 μg in asthmatics induces a decrease FEV1 and an increase level of the baseline nonspecific bronchial hyperresponsiveness. The aim was to determine the effect of prior inhalation of lower dose of LPS (corresponding to domestic airborne exposure in Strasbourg) on immediate bronchial response in mild cat allergic asthmatics.

Twenty subjects with an intermittent asthma sensitized to cat were included. Each subjects underwent 2 randomized cat allergen bronchial challenge (CABCT) test sessions precede (24 h), in double blind, by a “prior” nebulization of saline solution or 2 μg of LPS.

There were no significantly difference between the parameters (FEV₁, PEF, FEF 25-75) measured during the CABCTs when test performed after saline solution or LPS (p=0.173, 0.428, 0.839, respectively). There was no significant differences between PD20 Fel d1 after LPS versus saline solution exposure (p=0.42). No significant difference was seen in late bronchial response.

Our study demonstrated that exposure to low level of LPS (approximate the domestic airborne exposure in Strasbourg) did not enhance significantly airway responsiveness to cat allergen in cat allergic asthmatics.