Peyer’s patches

Peyer's patches are small masses of lymphatic tissue found in the small intestine, specifically in the ileum, which is the last part of the small intestine. They are named after the Swiss anatomist Johann Conrad Peyer. Peyer's patches are important components of the immune system by monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines.

Structure

Peyer's patches are oval-shaped areas of aggregated lymphoid follicles. They can be seen macroscopically as elongated thickenings of the intestinal wall. Each patch contains multiple follicles, which are densely packed with B cells, T cells, macrophages, and dendritic cells. These immune cells work together to detect and respond to pathogens passing through the gastrointestinal tract.

Function

The primary function of Peyer's patches is to contribute to the immune surveillance of the intestinal lumen and facilitate the generation of the immune response within the mucosa. They play a crucial role in the production of antibodys, particularly Immunoglobulin A (IgA), which is a type of antibody that plays a critical role in immune function in the mucous membranes.

Peyer's patches identify and capture antigens by means of specialized cells called M cells. These cells transport antigens from the intestine to the lymphoid follicles where they initiate an immune response. Following antigen exposure, B cells within the Peyer's patches differentiate into IgA-secreting plasma cells, which then migrate to various effector sites in the intestinal mucosa.

Clinical Significance

Peyer's patches are involved in several clinical conditions. They can become inflamed during infections, such as in typhoid fever, where they can become swollen and may even ulcerate. Additionally, they are involved in the pathogenesis of some inflammatory bowel diseases, such as Crohn's disease, where immune dysregulation is a key feature.

Research

Research on Peyer's patches has expanded our understanding of mucosal immunity and its role in protecting the body from pathogens. Studies have also explored the potential of targeting Peyer's patches for oral vaccine delivery, as they are an accessible site for inducing mucosal immunity.

See Also

• Lymphatic system
• Immune system
• Small intestine
• Mucosal immunity