Figure 2.

Immunohistochemical localisation of matrix metalloproteinases (MMPs) in a representative Crohn’s disease fistula. Sections of paraffin embedded fistula specimens with acute inflammation and granulation tissue (A–C) or chronic inflammation with fibrosis (D–F) were stained with anti-MMP-2 (A, D), anti-MMP-3 (B, E), and anti-MMP-9 (C, F). In acute inflammation with granulation tissue, MMP-2 staining was seen in endothelial cells, large mononuclear macrophage-like cells, and giant cells (A). MMP-3 staining was seen in large mononuclear macrophage-like cells and in giant cells (B) while MMP-9 staining was seen in small mononuclear leucocytes, granulocytes, and in giant cells (C). In chronic inflammation with fibrosis, MMP-2 and MMP-3 staining was seen in large mononuclear macrophage-like cells and fibroblasts (D, E) while MMP-9 staining was only observed in sporadic small mononuclear leucocytes and granulocytes (F). Magnification ×40.