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.
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.
Igarashi
H
H
Departments of Immunology, Pediatrics, and Cell Differentiation (Institute of Molecular Embryology and Genetics), Kumamoto University School of Medicine, Japan.
Kuwata
N
N
Kiyota
K
K
Sumita
K
K
Suda
T
T
Ono
S
S
Bauer
S R
SR
Sakaguchi
N
N
D000818:Animals; D015322:Gene Rearrangement, B-Lymphocyte; D016654:Genes, RAG-1 / Q000235:genetics / Q000276:immunology*; D049452:Green Fluorescent Proteins; D007114:Immunization; D008164:Luminescent Proteins / Q000235:genetics / Q000276:immunology*; D008221:Lymphoid Tissue / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D011948:Receptors, Antigen, T-Cell / Q000276:immunology
D008164:Luminescent Proteins; D011948:Receptors, Antigen, T-Cell; D049452:Green Fluorescent Proteins