Courtesy Katherine L. Knight and Ki-Jong Rhee © 2004 American Association of Immunologists
Left is a section of appendix following introduction of
Commensal or nonpathogenic bacteria have established a mutually beneficial relationship with the host immune system that allows them to reside peacefully within the lumen of a healthy host's gut. Lumenal colonization by diverse commensal species is essential for host health, permitting processing of indigestible carbohydrates and preventing colonization by pathogenic bacteria. But it's a delicate balance. "How [does the gut] maintain the necessary bacterial concentration but not become inflamed?" asks Andrew Neish, a pathologist at Emory University School of Medicine in Atlanta.
The way that bacteria cross the intestinal mucosa seems ...
