Immunohistochemical localization of anti-VCAM-1 antibody and pro-antibody accumulation in vivo in ApoE(−/−) and ApoE(+/+) mice. Anti-VCAM-1 antibody or pro-antibodies were administered to ApoE (− /− (A–J) or ApoE(+/+) (K–O) mice, and the indicated tissues were recovered after 24 hrs and analyzed for the presence of the antibody (A–E) or pro-antibody (F–O) by immunoperoxidase staining (indicated by brown color). Representative images (n = 4) of immunoperoxidase staining of tissues from mice injected with anti-VCAM-1 pro-antibody showed positive signal only in plaques, unlike tissues from anti-VCAM-1 antibody-treated mice. Original magnification: A,F,K: X10, B–E, G–J, L–O: ×20. Scale bars, 100 μm.