Recombination activating genes (RAG) induce secondary Ig gene rearrangement in and subsequent apoptosis of human peripheral blood circulating B lymphocytes.
Recombination activating gene (RAG) re-expression and secondary Ig gene rearrangement in mature B lymphocytes have been reported. Here, we have studied RAG expression of peripheral blood B lymphocytes in humans. Normal B cells did not express RAG1 and RAG2 spontaneously. More than a half of circulating B cells expressed RAG proteins, when activated with Staphylococcus aureus Cowan I (SAC) + IL-2. DNA binding activity of the RAG complex has been verified by a gel shift assay employing the recombination signal sequence (RSS). Secondary Ig light chain rearrangement in the RAG-expressing B cells was confirmed by linker-mediated (LM)-PCR. Highly purified surface kappa+ B cells activated by SAC + IL-2 became RAG+, and thereafter they started to express lambda chain mRNA. 2 colour immunofluorescence analysis disclosed that a part of the RAG+ cells derived from the purified kappa+ B cells activated by SAC + IL-2 turned to lambda+ phenotype in vitro. Similarly, apoptosis induction was observed in a part of the RAG+ B cells. Our study suggests that a majority of peripheral blood B cells re-expresses RAG and the RAG+ B lymphocytes could be eliminated from the B cell repertoire either by changing Ag receptor specificity due to secondary rearrangement or by apoptosis induction. Thus, RAG expression of mature B cells in peripheral blood would contribute to not only receptor revision for further diversification of B cell repertoire but in some cases (or in some B cell subsets) to prevention or induction of autoAb responses at this differentiation stage in humans.
Nagafuchi
H
H
Department of Immunology, St. Marianna University School of Medicine, Kawasaki, Kanagawa 216-8511, Japan.
Yoshikawa
H
H
Takeba
Y
Y
Nara
K
K
Miura
K
K
Kurokawa
M S
MS
Suzuki
N
N
D000328:Adult; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000276:immunology; D015322:Gene Rearrangement, B-Lymphocyte / Q000276:immunology*; D016654:Genes, RAG-1 / Q000276:immunology; D018398:Homeodomain Proteins / Q000097:blood*; D006801:Humans; D007376:Interleukin-2 / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D008875:Middle Aged; D009687:Nuclear Proteins; D012333:RNA, Messenger / Q000235:genetics; D013211:Staphylococcus aureus / Q000276:immunology
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D007376:Interleukin-2; D009687:Nuclear Proteins; C499311:RAG2 protein, human; D012333:RNA, Messenger; C064655:V(D)J recombination activating protein 2; C064658:RAG-1 protein