The present study aimed at assessing whether the non-enzymatic peroxidation of membrane phospholipids and the generation of leukotriene B₄ (LTB₄) are contributory factors in the pathogenesis of experimentally-induced feline lower airway inflammation. Twelve adult cats were investigated prior (control experiment) and subsequent to sensitisation and single aerosol exposure to Ascaris suum (AS) antigen. Airway responsiveness (C-Penh300 or concentration of carbachol inducing a 300% increase of Penh) was measured using barometric whole body plethysmography at 48 hours following saline or allergen challenge. Bronchoalveolar lavage fluid (BALF) and blood samples were collected 24 hours later. BALF was analysed for total and absolute differential cell counts and for LTB₄ quantification by enzyme immunoassay (EIA). Plasma lipid peroxides (PLP; spectrophotometrical OxyStat Kit (Biomedica)) and BALF 8-Isoprostaglandin F_2a (8-isoPGF_2a; EIA) were determined respectively as systemic and pulmonary markers of lipid peroxidation. Compared to control experiment, a single allergen challenge in AS-sensitised cats induced significant increases (P < 0.05) in BALF total cell count (188 versus 333 × 10³/ml), absolute number of eosinophils (13 versus 149 × 10³/ml) and 8-isoPGF_2a (232 versus 386 pg/ml) and a trend toward increased neutrophil number (15 versus 32 × 10³/ml; P = 0.06) and reduced C-Penh300 (0.026 versus 0.021 %; P = 0.08). BALF LTB₄ were significantly lower following AS-exposure (650 versus 210 pg/ml; P < 0.05) but no significant changes were detected for PLP. These findings suggest that: 1) unlike human asthma, BALF LTB4 levels are significantly decreased in AS-induced feline bronchial disease 2) oxidative stress occurs in lower airways of AS-challenged cats, leading to lipid peroxidation.

This abstract is funded by FRIA and Region wallonne.