Peyer's patch

Peyer's patches are organized lymphoid follicles located primarily in the ileum of the small intestine. They play a critical role in **immune surveillance** of the intestinal lumen by sampling antigens from the gut via specialized microfold cells (M cells), which deliver these antigens to underlying immune cells including macrophages, dendritic cells, T cells, and B cells. Upon antigen encounter, these immune cells can initiate an adaptive immune response that is further amplified in mesenteric lymph nodes before effector lymphocytes return to mucosal sites for action. Peyer's patches are also implicated in maintaining oral immune tolerance—helping distinguish between harmful pathogens and harmless dietary antigens or commensal microbes—though their exact role here remains under investigation[1][2][3]. Dysfunction or abnormal enlargement of Peyer's patches is linked to certain pathologies such as intussusception and may contribute to autoimmune conditions like Crohn's disease due to dysregulated local immunity[1][2]. Some orally administered postbiotic agents have been shown experimentally to activate specific dendritic cell populations within Peyer’s patches for broader immunomodulatory effects[3].

Other names

Peyer patchgut-associated lymphoid tissue (GALT) componentintestinal lymphoid follicle