title: Thymus-independent development and negative selection of T cells expressing T cell receptor alpha/beta in the intestinal epithelium: evidence for distinct circulation patterns of gut- and thymus-derived T lymphocytes.
abstract: We demonstrate that mouse intestinal intraepithelial lymphocytes (IEL) can be divided into subsets based on the differential expression of functional T cell receptor alpha/beta (TCR-alpha/beta) signaling complexes. Two subsets, CD4+ 8 alpha + beta - and CD8 alpha + beta -, are refractory to stimulation with anti-TCR-alpha/beta and contain high frequencies of potentially self-reactive cells. In contrast, the CD4+ and CD8 alpha + beta + IEL subsets are responsive to anti-TCR-alpha/beta and depleted of potentially self-reactive cells. The analysis of fetal liver radiation chimeras using adult thymectomized recipients demonstrates that the four TCR-alpha/beta + IEL subsets are generated in normal numbers in the absence of the thymus. Moreover, expression of the major histocompatibility complex class II-encoded I-E molecule and Mls1a in the gut of the athymic host results in the negative selection of potentially self-reactive T cells expressing V beta 11 and V beta 6, respectively, from those IEL subsets that express functional TCR-alpha/beta signaling complexes. Neither the spleen nor the Peyer's patches of athymic recipients contain T cells of donor origin. In contrast, normal numbers of phenotypically and functionally mature CD4+ and CD8 alpha + beta + T cells of donor origin are found in the lamina propria of chimeric animals. The phenotypic analysis of lymphocytes obtained from Ly5 congenic parabionts reveals that peripheral T cells migrate rapidly to the Peyer's patches and lamina propria, but not to the intestinal epithelium. Taken together, these results demonstrate that the intestinal epithelium is a thymus-independent site of T lymphopoiesis, where selection of the T cell repertoire involves the deletion of potentially self-reactive cells in situ. Moreover, the appearance of donor-derived, phenotypically mature T cells, exclusively in the lamina propria of athymic radiation chimeras, suggests that mature IEL expressing functional TCR-alpha/beta migrate to this site.
authors.affiliation: Department of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Poussier
authors.forename: P
authors.initials: P
authors.lastname: Edouard
authors.forename: C
authors.initials: C
authors.lastname: Lee
authors.forename: M
authors.initials: M
authors.lastname: Binnie
authors.forename: M
authors.initials: M
authors.lastname: Julius
mesh_terms: D000483:Alleles; D000818:Animals; D000950:Antigens, Ly / Q000235:genetics; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D004848:Epithelium / Q000276:immunology; D007422:Intestines / Q000276:immunology*; D051379:Mice; D008815:Mice, Inbred Strains; D010581:Peyer's Patches / Q000276:immunology; D011828:Radiation Chimera; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D000950:Antigens, Ly; D015704:CD4 Antigens; D016827:CD8 Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta