title: Early exposure to germs and the Hygiene Hypothesis.
abstract: A recent paper suggests that reduced exposure to germs results in the expansion of a cell type called natural killer T cells, which predisposes to colitis and asthma. Such a scenario could explain the Hygiene Hypothesis, which has been a puzzle for decades.
authors.affiliation: Division of Immunology, Karp Laboratories, Rm 10127, Children's Hospital Boston, Harvard Medical School, One Blackfan Circle, Boston, MA 02115, USA. dale.umetsu@childrens.harvard.edu
authors.forename: Dale T
authors.initials: DT
authors.lastname: Umetsu
mesh_terms: D000818:Animals; D001249:Asthma / Q000276:immunology / Q000473:pathology; D049109:Cell Proliferation; D003092:Colitis / Q000139:chemically induced / Q000276:immunology / Q000473:pathology; D004781:Environmental Exposure; D006801:Humans; D061148:Hygiene Hypothesis; D006967:Hypersensitivity / Q000276:immunology / Q000473:pathology; D007378:Interleukins / Q000276:immunology; D054892:Metagenome / Q000276:immunology*; D051379:Mice; D055611:Natural Killer T-Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D010081:Oxazolone / Q000009:adverse effects; D013047:Specific Pathogen-Free Organisms / Q000276:immunology
chemical_list: D007378:Interleukins; D010081:Oxazolone