Bronchoalveolar lavage activities for myeloperoxidase (MPO) and elastase activities in BALB/c and C57BL/6 mice following the sequential application of LPS and fMLP. Animals were intranasally challenged with LPS (0.3 mg/kg) or PBS alone (50 μl). Twenty four hours after the provocation, increasing concentrations of fMLP (0.5 to 5 mg/kg) or 50 μl of vehicle (PBS, 1% DMSO) were applied intranasally. Two hours after the second challenge, animals were sacrificed and bronchoalveolar lavage performed. Data are expressed as mean ± SEM from two different experiments each included 5–9 mice per group. Significance (P < 0.05), indicated by (*) or (#) is versus PBS-challenged/Vehicle-treated mice and LPS-challenged/Vehicle-treated mice, respectively.