title: Sugar-coated regulation of T cells.
abstract: The human gut is host to hundreds of different species of commensal bacteria that live in peaceful partnership with the host immune system. These commensal bacteria are far from neutral bystanders as they are intimately involved in the development of the immune system. Reporting in this issue of Cell, Kasper and colleagues (Mazmanian et al., 2005) reveal that a bacterial polysaccharide, PSA, produced by the commensal bacterium Bacteroides fragilis directs development of the immune system of the mouse host.
authors: Section of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors: Elizabeth E
authors: EE
authors: Eynon
authors: Lauren A
authors: LA
authors: Zenewicz
authors: Richard A
authors: RA
authors: Flavell
mesh_terms: D000818:Animals; D001441:Bacteroides fragilis / Q000737:chemistry / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D006801:Humans; D007107:Immune System / Q000187:drug effects / Q000254:growth & development / Q000276:immunology; D051379:Mice; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000276:immunology / Q000494:pharmacology; D013154:Spleen / Q000276:immunology
chemical_list: D011135:Polysaccharides, Bacterial