E229K thrombin attenuated C5a-induced alveolitis in WT but not in proCPB^−/− mice. C5a (0.1 mg/mL) or saline control was instilled endotracheally in WT (□) or proCPB^−/− (▪) mice. E229K thrombin or saline control was administered intravenously into the right jugular vein 5 minutes before the C5a instillation. Six hours later, BAL was performed and total WBC counts (A) and protein contents (B) in the BAL fluids were determined. (n = 6 in each group). Data are presented as mean ± SD. *P < .05; **P < .01.