Airway hyperresponsiveness. AHR was assessed 24-hours after the last pulmonary challenge in C5-sufficient (solid bars) and C5-deficient (diagonal bars) mice. Values are reported as the percent increase in Penh of each dose of methylcholine relative to PBS aerosolization. Each value is the mean ± SEM for three experiments; n = 14 mice per group in three experiments for immunized and challenged mice. * indicates p < 0.05 for C5-sufficient compared to C5-deficient at each MCh dose, p = 0.0026 at the 25 mg/ml MCh dose and p < 0.0001 at the 50 mg/ml MCh dose.