The mucosa of the colon occupies 25% of the intestinal wall, from themuscularis mucosato the lumen-lining epithelium, and contains a variety of cell types, predominantly B and T lymphocytes, but also monocytes, mast cells, and macrophages (1 ,2 ). These cells secrete a variety of cytokines, including interleukins, leakotrienes, and prostaglandins. Most of these are locally active, diffuse throughout the mucosa, and do not substantially contribute to the concentration of cytokines in the blood.
