Mucosa-associated lymphoid tissue comprises lymphoid follicles in mucosal linings that defend against pathogens.
Mucosa-associated lymphoid tissue (MALT) is a diffuse collection of non-encapsulated lymphoid tissue found throughout mucosal surfaces of the body. It plays a critical role in the immune surveillance and defense of mucosal membranes — which are common entry points for pathogens. MALT includes organized structures like Peyer’s patches as well as scattered immune cells embedded in mucosa.
MALT is widely distributed in the following systems:
Type | Location | Examples |
---|---|---|
GALT (Gut-associated lymphoid tissue) | Intestinal mucosa | Peyer’s patches, appendix, isolated lymphoid follicles |
BALT (Bronchus-associated lymphoid tissue) | Bronchial walls and lungs | Subepithelial lymphoid clusters in bronchioles |
CALT (Conjunctival-associated lymphoid tissue) | Eye conjunctiva | Lymphoid follicles along the inner eyelid |
SALT (Skin-associated lymphoid tissue) | Dermis and epidermis | Langerhans cells, dermal dendritic cells |
MALT is present in many vertebrates. In mammals, particularly humans, it has evolved to provide strong mucosal immunity due to high antigen exposure from the environment, diet, and airborne particles.