| Project/Area Number |
12450334
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生物・生体工学
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| Research Institution | Okayama University |
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Principal Investigator |
OHMORI Hitoshi Okayama University, Biotechnology, Professor, 工学部, 教授 (70116440)
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| Co-Investigator(Kenkyū-buntansha) |
KANAYAMA Naoki Okayama University, Biotechnology, Lecturer, 工学部, 講師 (70304334)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥12,700,000 (Direct Cost: ¥12,700,000)
Fiscal Year 2002: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2001: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | Antibody / antibody genes / affinity maturation / somatic mutation / transgenic mouse / B lymphocytes / germinal center / gene rearrangement / 遺伝子再編成 / V(D)J再構成 / RAG遺伝子 / IL-7 / V(D)J再構 |
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| Research Abstract |
Recently, peripheral B cells have been shown to undergo secondary V(D)J rearrangement of Ig genes, but the physiological role of this event has not been fully elucidated. Here, we investigated whether rearrangement of L chain genes in the periphery is involved in the generation of high-affinity Abs. To test this possibility, we used a 17.2.25 rearranged VHDJH gene (VHT)-knockin mouse whose B cell diversity is limited due to the expression of the site-directed transgene. Immunization of the mouse with p-nitrophenylacetyl (pNP)-conjugated chicken γ-globulin (CGG) preferentially led to the production of anti-pNP IgG Abs comprised of non-VHT-encoded H chains and λ chains, which constituted a majority of high-affinity IgG to this hapten. We isolated three independent anti-pNP IgG1 mAbs (two bearing λ1 with high-affinity and one bearing κ with low-affinity), all of which used a common VHDJH containing an identical point mutation, thus suggesting that κ to λ1 replacement contributed to an increase of the Ab affinity. RAG-2 mRNA and the recombination signal sequence break reflecting the λ1 gene rearrangement were detected in the draining lymph node (LN) of immunized mice, but not of non-immunized animals. There was a close correlation between the levels of the λ gene rearrangement and λ^+ high-affinity anti-pNP IgG. Thus, our findings suggest that new rearrangement of λ genes in the periphery contributes to affinity maturation of anti-pNP IgG.
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