| Project/Area Number |
06670488
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
内科学一般
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
ISHIBASHI Hiromi KYUSHU UNIVERSITY, FACULTY MEDIINE, ASSOCIATE PROFESSOR, 医学部, 助教授 (80127969)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHIDA Kazuhiro KYUSHU UNIVERSITY, FACULTY MEDIINE, INSTRUCTOR, 医学部, 助手 (60180981)
NAKAMURA Minoru KYUSHU UNIVERSITY, FACULTY MEDIINE, INSTRUCTOR, 医学部, 助手 (40217906)
工藤 二郎 九州大学, 医学部, 助手 (90148940)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Primary biliary cirrhosis / Autoimmune disease / Immunoglobulin gene / HLA / T cell / T cell epitope / Molecular mimicry / Immune response / 自己抗体 / エピトープ |
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| Research Abstract |
1.Analysis of mitochondria antigen (PDC-E2) specific-immunoglobulin gene
We examined the nucleotide sequence and predicted amino acid sequence of the expressed variable regions of three IgG anti-PDC and OGDC mAb secreted by monoclonal B cell lines established from peripheral blood B lymphocytes of a patient with PBC.All mAbs were revealed to use different VH, VL, and D segment genes each other, and these genes which they used were previously reported to be used by various antibodies both to exogenous and endogenous antigen. Therefore PBC-related IgG anti-PDC and OGDC antibody possibly do not use the specific gene segment. We also identified the existence of somatic hypermutation in the expressed mAb82VH, therefore suggested the importance of somatic hypermutation and antigen-driven selection on the appearance of high-affinity anti-PDC and OGDC antibody.
2. Cloning of T cell specific for mitochondrial antigen and epitope mapping
We established six T cell clones specific for PDC-E2 peptides
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from four different patients with PBC using 33 different peptides of 17-20 amino acid residues correponding to human PDC-E2 as stimulating antigens (Ags). The minimal T cell epitopes of these six T cell clones were all mapped to the same region of the PDC-E2 peptide 163-176 (GDLLAEIETDKATI). The HLA restriction molecules for this epitope were all identified as HLA DRB4 0101. The common essential amino acids of this epitope for these T cell clones were E, D and K at positions 170, 172 and 173, respectively, and amino acid D at position 172 is a critical MHC binding site for all T cell clones tested. One T cell clone cross-reacted to exogenous Ags such as E.coli PDC-E2 peptide which has an EXDK sequence. This is the definite demonstration of the presence of molecular mimicry at the T cell clonal level in human autoimmune diseases.
3. HLA DR DNA typing of PBC patients.
Forty-eight patients with primary biliary cirrhosis (PBC) and 336 healthy individuals were examined for HLA-DR, DQ and DP alleles by DNA typing based on the polymerase chain reaction (PCR) -sequence specific oligonucleotide probe (SSOP) method. Frequencies of HLA-DRB1^* 1602, DRB1^* 0803, DQB1^* 0502, DQB1^* 0601 and DPB1^* 0202 were found to be increased in the patients. The susceptibility to PBC was suggested to be controlled by the HLA-DRB1 locus. In contrast, the frequency of HLA-DQB1^* 0302 was decreased in the patients, suggesting that the resistance to PBC may be controlled by the HLA-DQ locus. Less
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