Localization of recombination activating gene 1/green fluorescent protein (RAG1/GFP) expression in secondary lymphoid organs after immunization with T-dependent antigens in rag1/gfp knockin mice

• Published in: Blood 2001-05, Vol.97 (9), p.2680-2687
• Main Authors: IGARASHI, Hideya, KUWATA, Naomi, KIYOTA, Kumiko, SUMITA, Kiminobu, SUDA, Toshio, ONO, Shiro, BAUER, Steven R, SAKAGUCHI, Nobuo
• Format: Article
• Language: English
• Subjects: Analysis of the immune response. Humoral and cellular immunity; Animals; Antibody production; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Gene Rearrangement, B-Lymphocyte; Genes, RAG-1 - genetics; Genes, RAG-1 - immunology; Green Fluorescent Proteins; Immunization; Immunobiology; Luminescent Proteins - genetics; Luminescent Proteins - immunology; Lymphoid Tissue - immunology; Mice; Mice, Knockout; Receptors, Antigen, T-Cell - immunology
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V97.9.2680

Secondary rearrangements of immunoglobulin gene segments that generate a new antibody repertoire in peripheral B cells have been described as receptor revision and occur by as yet unknown mechanisms. To determine the importance of recombination activating gene (RAG) expression in receptor revision, heterozygous rag1/green fluorescent protein (gfp) knockin mice were used to examine the location of RAG1 expression in the germinal centers (GCs) of lymphoid follicles after immunization with a variety of T-cell-dependent antigens. Immunization of rag1/gfp heterozygous mice or rag1 homozygous knockout mice reconstituted with rag1/gfp heterozygous spleen cells caused the down-regulation of RAG1/GFP signal in GCs. Although some RAG1/GFP(+) cells appeared in regions surrounding the peanut agglutinin (PNA)(+)GL-7(+) GC area, RAG1/GFP(+) cells did not accumulate in the central region. In addition, the stimulation of spleen B cells with anti-mu antibody plus interleukin-4 (IL-4) or with anti-CD40 monoclonal antibody plus IL-7 did not induce GFP signals at detectable levels in vitro. These results clearly demonstrate that RAG1 re-expression either does not occur or is at extremely low levels in antigen-driven B cells in GCs of secondary lymphoid follicles, suggesting that other mechanisms may mediate the gene rearrangements observed in receptor revision.