title: Expression of recombination-activating gene in mature peripheral T cells in Peyer's patch.
abstract: Recombination-activating gene (RAG) 1 and 2 are essential for the gene rearrangement of antigen receptors of both T and B cells. To investigate RAG gene expression in peripheral lymphoid organs other than the thymus and bone marrow, we established mice in which a green fluorescent protein (GFP) gene is knocked-in the RAG2 gene locus (RAG2-GFP mice). In the thymus and bone marrow of heterozygous RAG2-GFP mice, as expected, GFP expression was detected in the appropriate stages of developing T and B cells. Interestingly, only a fraction of Thy-1.2(+) cells in the Peyer's patch were found to be GFP(+) amongst the peripheral lymphoid organs. The GFP(+) cells expressed high levels of surface TCRbeta and CD3, suggesting mature T cells with rearranged TCRalphabeta. However, they showed activated/memory phenotypes, i.e. CD45RB(low), CD69(high), CD44(high) and CD62L(low), and belonged to a CD4(+)CD8(+) population expressing c-kit, IL-7R and pTalpha characteristic of immature developing lymphocytes. Moreover, RAG(+) Peyer's patch T cells seem to be of thymic origin as judged by their expression of CD8alphabeta. These results show that there exists a fraction of mature T cells expressing RAG genes in the Peyer's patch, implying a potential for a secondary rearrangement of TCR in extrathymic tissues.
authors.affiliation: Laboratory for Immune Regulation, RIKEN Research Center for Allergy and Immunology, and Department of Molecular Immunology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Kondo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wakao
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Koseki
authors.forename: Toshitada
authors.initials: T
authors.lastname: Takemori
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kojo
authors.forename: Michishige
authors.initials: M
authors.lastname: Harada
authors.forename: Minako
authors.initials: M
authors.lastname: Takahashi
authors.forename: Sakura
authors.initials: S
authors.lastname: Sakata
authors.forename: Chiori
authors.initials: C
authors.lastname: Shimizu
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ito
authors.forename: Toshinori
authors.initials: T
authors.lastname: Nakayama
authors.forename: Masaru
authors.initials: M
authors.lastname: Taniguchi
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D017930:Genes, Reporter; D006579:Heterozygote; D051379:Mice; D018345:Mice, Knockout; D010581:Peyer's Patches / Q000502:physiology*; D011993:Recombinant Fusion Proteins; D011995:Recombination, Genetic; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C499308:Rag2 protein, mouse; D011993:Recombinant Fusion Proteins; C064655:V(D)J recombination activating protein 2