2003 Fiscal Year Final Research Report Summary
Study of immunotherapy targeted on autoimmune T cell of myasthenia gravis
| Project/Area Number |
13670636
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Neurology
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| Research Institution | Kanazawa University |
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Principal Investigator |
YOSHIKAWA Hiroaki Kanazawa University, Health service Center, Associate Professor, 保健管理センター, 助教授 (10272981)
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| Co-Investigator(Kenkyū-buntansha) |
IWASA Kazuo Kanazawa University, University Hospital, Lecture, 医学部附属病院, 講師 (10345613)
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| Project Period (FY) |
2001 – 2003
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| Keywords | myasthenia gravis / immunosuppressant / tacrolimus / SCID mice / intracellular Ca^<2+> level |
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| Research Abstract |
We evaluated anti-acetylcholine receptor antibody (AChRAb) and IgG productions from thymus cells, bone marrow, and peripheral blood mononuclear cells(PBMC) in patients with myasthenia gravis(MG). PBMC from MG patients spontaneously produced more abundant IgG than that from normal controls. PBMC of MG patients had an accelerated ability to produce immunoglobulin compared to that of thymus or bone marrow cells. Severe combined immunodeficiency(SCID) mice do not have functional T or B cells, and injected human lymphocytes can reconstitute a functional human immune system in the mice. We produced MG-SCID mice by injecting thymus cells and PBMC into the peritoneal cavity of the mice. One hundred days after cell transplantation, we injected acetylcholine receptor protein into the peritoneal cavity of the mice. We observed a sharp elevation of human AChRAb titer after the antigen administration suggesting a memory immune response of human lymphocytes. In a study to clarify factors that induce immunoglobulin production by cultured PBMC, we observed that interleukin (IL)-5 and IL-6 secretions are correlated with IgG production. As a result, immunotherapy targeting PBMC from MG patients seems to be effective. A clinical trial of tacrolimus proved to be effective for intractable MG patients. Currently, the usage of tacrolimus is admitted as an immunotherapy for intractable MG patients. As tacrolimus showed quick therapeutic effect compared to other immunosuppressants, pharmacological effects in addition to immunosuppression are suspected. We measured intracellular Ca^<2+> level ([Ca^<2+>]_i) in cultured skeletal muscle cell line (TE671). Tacrolimus increased [Ca^<2+>]_i induced by the addition of acetylcholine. Therefore, tacrolimus may have an effect on the excitation-contraction coupling as well as immunosuppressive effects.
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