Gut associated lymphoid tissue

General Information
Latin	textus lymphoideus intestinalis
Greek
TA98
TA2
FMA
Details
System	Immune system
Artery
Vein
Nerve
Lymphatic drainage
Precursor
Function
Identifiers
Clinical significance
Notes

Gut-associated lymphoid tissue (GALT) is a component of the mucosa-associated lymphoid tissue (MALT) which works in the immune system to protect the body from invasion in the gastrointestinal tract.

Structure

GALT is composed of several types of lymphoid tissues that are found throughout the gastrointestinal tract. These include:

Peyer's Patches

Peyer's patches are small masses of lymphatic tissue found throughout the ileum region of the small intestine. They are an important part of the immune system by monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines.

Isolated Lymphoid Follicles

Isolated lymphoid follicles are single lymphoid follicles found throughout the small intestine and large intestine. They are similar to Peyer's patches but are not aggregated.

Appendix

The appendix is a narrow, finger-shaped pouch that projects out from the cecum of the large intestine. It contains a large amount of lymphoid tissue and is considered part of the GALT.

Tonsils

The tonsils are collections of lymphoid tissue located at the entrance of the pharynx. While not directly part of the gut, they are considered part of the MALT system and play a role in the immune response to ingested or inhaled pathogens.

Function

The primary function of GALT is to protect the body from invasion by pathogens that enter the body through the gut. It does this by:

Immune Surveillance

GALT contains a large number of immune cells, including T cells, B cells, macrophages, and dendritic cells. These cells are responsible for detecting and responding to pathogens.

Antigen Sampling

Specialized cells known as M cells are found in the epithelium overlying Peyer's patches. These cells are responsible for sampling antigens from the gut lumen and delivering them to the underlying immune cells.

Immune Response

Upon detection of a pathogen, GALT initiates an immune response. This can include the production of antibodies by B cells, the activation of T cells, and the release of cytokines to recruit additional immune cells.

Clinical Significance

GALT plays a crucial role in maintaining gut health and preventing infections. Dysfunctions in GALT can lead to:

Inflammatory Bowel Disease

Conditions such as Crohn's disease and ulcerative colitis are associated with abnormal immune responses in the gut, which may involve GALT.

Infections

Pathogens such as Salmonella, Shigella, and Helicobacter pylori can exploit weaknesses in GALT to establish infections.

Immune Tolerance

GALT is also involved in the development of immune tolerance to dietary antigens and commensal bacteria, preventing unnecessary immune responses that could lead to food allergies or autoimmune diseases.

See Also

• Mucosa-associated lymphoid tissue
• Immune system
• Peyer's patches
• Appendix

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