Disease of the immune system - Rejection of transplants

6 important questions on Disease of the immune system - Rejection of transplants

What is the major antigenic differences between a donor and recipient that result in rejection of transplants

Differences in HLA alleles

What is characteristic of hyperacute graft rejection?

  • mediated by pre-existing antibodies against graft antigens. complement activation within graft blood vessels is induced (inflammation, fibrosis and tissue necrosis)
  • Can cause: thrombosis, ischemic damage, and rapid graft failure
  • Not common, because donor and recipient are matched before transplantation
  • hours-days

What is characteristic of acute graft rejection (cellular)?

  • mediated by T cells (cellular rejection)
  • CD8+ T cells kill graft cells directly and/or
  • CD4+ T cells induce inflammation by cytokine production or macrophage/neutrophil recruitment
  • Main cause of early graft failure – immunosuppressive therapy usually successful
  • Morphology:
    • 1) interstitial inflammation of tissue,
    • 2) vascular inflammation or necrosis of vessel walls
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What is characteristic of acute graft rejection (humoral)?

  • Antibodies against alloantigens bind to vascular endothelium, triggering classical complement activation, inflammation and tissue damage
  • Morphology: inflammation of small blood vessels, associated with deposition of complement factors

What is characteristic of chronic graft rejection?

  • Chronic secretion of pro-inflammatory cytokines activates proliferation and activation of fibroblasts and smooth muscle cells
  • Morphology: Interstitial tissue fibrosis, narrowing of blood vessels and thickening of vessel walls
  • Slow progressive loss of graft function - No successful therapies
  • after months

What is Graft-versus-Host Disease (GvHD) and give an example of transplantation that can cause this

  1. Cells of the graft s recognize alloantigens in the host and attack host tissues and reject the host. It can be acute or chronic.
  2. Hematopoietic Stem Cell (HSC) Transplantation. Transplantation of multipotent stem cells, usually derived from bone marrow or umbilical cord blood

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