C5a-induced alveolitis in WT and proCPB^−/− mice. Representative lung tissue samples of C5a-induced alveolitis from WT mice in the absence (A) or presence (B) of pretreatment with E229K thrombin and from proCPB^−/− mice in the absence (C) or presence (D) of pretreatment with E229K thrombin. Black arrows show macrophages. Images at 200× total magnification were visualized using a Zeiss Axiovert 40 CFL microscope equipped with an A-plan 20×/0.30 numerical aperture ph1 objective lens (Zeiss, Dublin, CA). Images were captured and rendered using a Zeiss AxioCam camera and AxioVision AC software.