Keeping the Gut Microflora at Bay

Abstract
The commensal microflora of the gut provide benefits to the host. They help to digest dietary carbohydrate and to maintain the appropriate balance among different microbial species so that the chance of gut colonization by pathogenic bacteria is reduced. In their Perspective, Kraehenbuhl and Corbett discuss new work (MacPherson and Uhr) that reveals how the host's mucosal immune response prevents commensal bacteria from straying beyond the gut mucosa where they might induce an unwanted systemic inflammatory immune response.