Allan McI. Mowat

TL;DR: The unique aspects of the local microenvironment of the intestinal immune system are reviewed and how these promote the development of regulatory responses that ensure the maintenance of homeostasis in the gut are discussed.

TL;DR: The anatomical and physiological distinctions that are observed in the small and large intestines are detailed, and it is suggested how these may account for the diversity in the immune apparatus that is seen throughout the intestine.

TL;DR: It is found that embryonic precursor cells seeded the intestinal mucosa and demonstrated extensive in situ proliferation during the neonatal period, but these cells did not persist in the intestine of adult mice and were replaced around the time of weaning by the chemokine receptor CCR2–dependent influx of Ly6Chi monocytes that differentiated locally into mature, anti-inflammatory macrophages.

TL;DR: A model of stepwise induction of oral tolerance is proposed in which specialized populations of mucosal dendritic cells and the unique microenvironment of draining mesenteric lymph nodes combine to generate regulatory T cells that undergo subsequent expansion in the small intestinal lamina propria.

TL;DR: Five experts are asked to discuss the issue of heterogeneity in the mononuclear phagocyte system and to give their opinion on the importance of defining these cells for future research.