title: Continued expression of recombination-activating genes and TCR gene recombination in human peripheral T cells.
abstract: It has been reported that a small population of peripheral T lymphocytes are capable of expressing V(D)J recombinase and initiating secondary V(D)J rearrangements. To determine whether RAG-expression and secondary TCR gene recombination in peripheral T cells are an antigen-driven process in secondary lymphoid tissues, we examined naive CD4(+) T cells, activated/memory CD4(+) T cells, and germinal center T cells from human tonsils. Our results showed that low levels of RAG-1 and RAG-2 mRNA were present in all T cell subpopulations except CD3(+)/CD4(-) T cells. LM-PCR analyses for double-strand DNA breaks showed that all the T cell subsets expressing RAG genes contain double-strand signal break ends, indicating ongoing TCR gene recombination. Continued RAG gene expression, introducing and repairing of double-strand DNA breaks at the TCR loci in the periphery may have significant implications in the development of some T cell neoplasms.
mesh_terms: D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics*; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D016654:Genes, RAG-1; D006801:Humans; D007133:Immunoglobulin Joining Region / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D009687:Nuclear Proteins; D011995:Recombination, Genetic; D013601:T-Lymphocytes / Q000378:metabolism*; D014178:Translocation, Genetic
chemical_list: D004268:DNA-Binding Proteins; D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D009687:Nuclear Proteins; C499311:RAG2 protein, human; C064655:V(D)J recombination activating protein 2