A big challenge of the immune system in the intestine is being able to distinguish between harmful pathogens and at the same time be tolerant towards harmless antigens derived from food and commensal bacteria (good bacteria). Mechanisms to maintain tolerance are therefore necessary to avoid unwanted immune responses that may lead to inflammatory bowel diseases (IBD) like Crohn’s disease or ulcerative colitis. The dendritic cells (DCs) found in the intestine are crucial to maintaining this equilibrium. DCs are constantly sampling antigens, such as food antigens. One way these cells sample antigens directly from the intestinal lumen is by inserting their dendritic processes between the epithelial cells layer .
The T cells found in the epithelium located between intestinal epithelial cells are called intraepithelial lymphocytes (IELs) and are thought to contribute to intestinal homeostasis by regulating the turnover of IECs and secreting hormones for epithelial repair .
Below are some resources in case you are interested in learning more about the immune system in the intestine.
- Review by Nature Reviews Immunology: Regional specialization within the intestinal immune system
- Video Protocol: How to Prepare Lamina Propria from Mouse Intestine – Tissue Dissociation Protocol
- Nature Protocol Figure: Stepwise procedure for the dissection of the mesentery
1. Dendritic cells express tight junction proteins and penetrate gut epithelial monolayers to sample bacteria. Nat Immunol. 2001 Apr;2(4):361-7
2. Intestinal T cells: facing the mucosal immune dilemma with synergy and diversity. Semin Immunol. 2009 Jun;21(3):130-8