Lysozyme (muramidase) is a protein with a molecular weight of approx. 15 kD that belongs to the group of alkaline glycosidases. Lysozyme is made by granulocytes, monocytes, and macrophages. The main source of fecal lysozyme is the intestinal granulocytes. Lysozyme can be detected in all cells of the inflammatory infiltrate during an acute attack of Crohn‘s disease. To some extent, Lysozyme is also secreted actively into the bowel lumen by mononuclear cells.