title: Lymphoid hyperplasia, autoimmunity, and compromised intestinal intraepithelial lymphocyte development in colitis-free gnotobiotic IL-2-deficient mice.
abstract: IL-2-deficient (IL-2(-/-)) mice develop disorders of the hemopoietic and immune systems characterized by anemia, lymphocytic hyperplasia, and colitis. The mechanisms responsible for these abnormalities remain unclear. To investigate the underlying basis of autoimmunity, the particular role of commensal gut flora in the initiation of colitis, and the role of IL-2 in the development of intestinal intraepithelial lymphocytes (iIEL), we evaluated IL-2(-/-) mice reared and maintained under gnotobiotic (germfree) conditions. By 8 wk of age, 80% (20 of 25) of germfree IL-2(-/-) mice show signs of disease, including anemia, disturbances in bone marrow hemopoietic cells, lymphocytic hyperplasia, and generalized autoimmunity, similar to those seen in specific pathogen-free (SPF) IL-2(-/-) mice. In striking contrast to SPF IL-2(-/-) mice, germfree IL-2(-/-) mice do not develop colitis. However, the numbers of gammadelta+ and TCR alphabeta+ CD8 alphaalpha+ iIELs are reduced, and in lethally irradiated SPF IL-2(+/+) mice, reconstituted with IL-2(-/-) bone marrow TCR gammadelta+ iIELs fail to develop, consistent with an important role of IL-2/IL-2R signaling in the development of gammadelta iIELs. Consequently, our findings demonstrate that the colitis seen in SPF IL-2(-/-) mice depends upon the presence of intestinal bacterial flora and that environmental Ags are not responsible for the anemia and extraintestinal lymphoid hyperplasia that occur in IL-2(-/-) mice. Thus, germfree IL-2(-/-) mice represent a unique system in which the role of IL-2 deficiency in hemopoietic and immune system disorders can be investigated in dissociation from complications that may arise due to colitis.
authors.affiliation: Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia 19104-6076, USA.
authors.forename: N V
authors.initials: NV
authors.lastname: Contractor
authors.forename: H
authors.initials: H
authors.lastname: Bassiri
authors.forename: T
authors.initials: T
authors.lastname: Reya
authors.forename: A Y
authors.initials: AY
authors.lastname: Park
authors.forename: D C
authors.initials: DC
authors.lastname: Baumgart
authors.forename: M A
authors.initials: MA
authors.lastname: Wasik
authors.forename: S G
authors.initials: SG
authors.lastname: Emerson
authors.forename: S R
authors.initials: SR
authors.lastname: Carding
mesh_terms: D000367:Age Factors; D000818:Animals; D015551:Autoimmunity; D001854:Bone Marrow Cells / Q000276:immunology; D003092:Colitis / Q000276:immunology; D005434:Flow Cytometry; D005856:Germ-Free Life; D006410:Hematopoiesis; D007108:Immune Tolerance; D018928:Immunity, Mucosal; D007376:Interleukin-2 / Q000172:deficiency*; D008099:Liver / Q000166:cytology; D016131:Lymphocyte Subsets / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism; D013154:Spleen / Q000166:cytology
chemical_list: D007376:Interleukin-2; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta