C3d deposition in eyes exposed to smoke. Localization of the complement activation product, C3d, one of the C3 opsonins that binds covalently to (cell) membranes was identified using immunohistochemistry, comparing WT (A,B) or CFB −/− mice (C,D) exposed to room air (A,C) or cigarette smoke (CE) (B,D). Alternative complement pathway deficiency ameliorates chronic smoke-induced functional and morphological ocular injury: Woodell A, Coughlin B, Kunchithapautham K, Casey S, Williamson T, Ferrell WD, Atkinson C, Jones BW, Rohrer B - PloS one (2013). Not altered. CC.