Rejection reaction

Japanese: 拒絶反応 - きょぜつはんのう

Also called rejection. When an organ or tissue from one individual is transplanted into another, the blood supply is restored and the transplant appears successful for the first 7 to 10 days, but eventually inflammation occurs, lymphocytes and mononuclear cells leak out, and the transplant necrotizes and falls off. This is called rejection, and it can be seen in vertebrates that have evolved to a certain degree, not only in different species but also in the same species, and it causes various symptoms after organ transplantation and leads to failure. Rejection occurs when the donor has an alloantigen called histocompatibility antigen (HLA) that the recipient does not have, causing an immune reaction in the recipient. Since this antigen is genetically determined, rejection rarely occurs between identical twins or purebred animals. To alleviate rejection, transplants are now performed between individuals with similar histocompatibility antigen types, and immunosuppressants such as cyclosporine are administered after transplantation, which has increased the success rate of transplants.
→ Related topics Xenogeneic organ transplantation | Graft-versus-host disease | Cellular immunity | Kidney transplantation | Heart transplantation | Living donor liver transplantation | Living donor small intestine transplantation | Hematopoietic stem cell transplantation | Delayed reaction | Immunosuppressants

Source : Heibonsha Encyclopedia About MyPedia Information

Japanese:

拒否反応とも。一個体の臓器や組織を他の個体に移植すると，当初の７〜10日間血液供給も回復し成功したようにみえても，やがて炎症を起こし，リンパ球，単核球が浸出し，移植物は壊死(えし)して離脱する。これが拒絶反応で，異種はもちろん同種でも，ある程度以上進化した脊椎動物にみられ，臓器移植後各種の症状を起こして失敗の原因となる。拒絶反応は，組織を与える個体が，受け取る個体にない組織適合抗原（HLA）と呼ばれる同種抗原を有するために，受け取る個体が免疫反応を起こすことによる。この抗原は遺伝的に決定されるので一卵性双生児や純系動物間では拒絶反応はほとんど起こらない。拒絶反応を軽くするために，組織適合抗原の型の近い個体間で移植を行ったり，移植後シクロスポリンなどの免疫抑制剤の投与が行われるようになり，移植の成功率が高くなった。
→関連項目異種間臓器移植｜移植片対宿主反応病｜細胞性免疫｜腎移植｜心臓移植｜生体肝移植｜生体小腸移植｜造血幹細胞移植｜遅延反応｜免疫抑制剤

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