Hyaluronidase (HYAL) induces mononuclear cell increase in bronchoalveolar space by mechanism partially dependent on lipid mediators. (A) Leukotriene (LT)B4 presents in the supernatant of lung homogenates were analysed by specific electroimmunoassay. C57Bl/6 was inoculated intranasally (i.n.) with 16 U of bovine testicular HYAL or phosphate buffered saline (PBS) and the lungs were removed 96 h later. Values represent means ± standard error of mean (SEM); n = 10; P = 0.04 compared to the PBS; t test was used. (B) Prostaglandin E2 concentration in the supernatant of lung homogenates was analysed by specific electroimmunoassay. C57Bl/6 was inoculated i.n. with 16 U of bovine testicular HYAL or PBS and the lung was removed 96 h later. Values represent means ± SEM; n = 10; P = 0.15 compared to the PBS group, t test was used. (C) Pre-treatment with dexamethasone (1 mg/kg s.c.); MK886 (5 mg/kg/0.5 mL by gavage) or celecoxib (5 mg/kg/0.5 mL by gavage) significantly reduced the number of cells in bronchoalveolar space of C57Bl/6 mice. All treatments were performed 1 h before stimuli and every 24 h until the end of experiment. Control received only PBS. Values represent means ± SEM.; n = 5; * P > 0.01 compared to PBS; # P > 0.001 compared to HYAL + PBS, ANOVA test was used. (C) Mononuclear cells recruitment to the bronchoalveolar space of 5-LO -/- (129-Alox5tm1Fun) mice is decrease when compared to strain-matched wild-type (WT) mice. Each strain was inoculated with 16 U of HYAL and cells recovered 96 h after stimulus. Values represent means ± SEM; n = 5; * P < 0.0001 compared to PBS WT; # P = 0.0003 compared to PBS 5-LO -/-; # P = 0.0003 compared to HYAL WT; test t was used.