Mucosa-associated lymphoid tissue


The mucosa-associated lymphoid tissue, also called mucosa-associated lymphatic tissue, is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body, such as the gastrointestinal tract, nasopharynx, thyroid, breast, lung, salivary glands, eye, and skin. MALT is populated by lymphocytes such as T cells and B cells, as well as plasma cells and macrophages, each of which is well situated to encounter antigens passing through the mucosal epithelium. In the case of intestinal MALT, M cells are also present, which sample antigen from the lumen and deliver it to the lymphoid tissue. MALT constitute about 50% of the lymphoid tissue in human body.

Categorization

The components of MALT are sometimes subdivided into the following:
It can be also distinguished by level of organization of the tissue:
MALT plays a role in regulating mucosal immunity. It may be the site of lymphomas, usually a non-Hodgkin lymphoma. A specific entity is the marginal zone B-cell lymphoma. Certain subtypes of marginal zone B cell lymphomas such as those occurring in the stomach are commonly caused by Helicobacter pylori infection.