Digestive system Physiology-Immune Functions
Immune Function of the Gastrointestinal Tract
The mass of immuno-competent lymphoid cells and tissue in the GI tract is equivalent to that found in the rest of the body. Immunocytes can be found in the mucosa and submucosa and within Peyer patches in the terminal ileum. These immunocytes include T and B lymphocytes, plasma cells, mast cells, macrophages, and eosinophils. When they encounter an antigen, they respond by secreting inflammatory mediators (e.g., histamine, prostaglandins, leukotrienes, and cytokines). These stimulate GI motility and the secretion of water and electrolytes, thus promoting expulsion of the offending antigen.The figure summarizes the immune defenses of the GI tract. Some of clinical conditions are defined in the following figure.