questions 0

Transplant

Topic updated on 09/23/17 5:25pm

Snapshot
  • A 55-year-old-woman presents with nausea and yellowing of the skin to her primary care physician. Medical history is significant for a liver transplantation approximately 1.5 weeks prior to presentation. On physical examination there is scleral icterus and mild ascites. A liver biopsy shows lymphocytic infiltrates in the interstitium. (Acute rejection)
Introduction
  • Transplantation is a process by which
    • cells, tissues, or organs (graft) from the donor are transplanted into a host (or recipient)
  • The immune system's ability to recognize and respond to foreign antigens bring challenges to transplantation
  • There are several types of grafts
    • autograft
      • tissue is moved from one location to another in the same person
        • e.g., skin graft and using the saphenous vein to replace a coronary artery
      • the graft will not be considered foreign and will not require lifelong immunosuppresion
    • syngeneic graft (isograft)
      • tissue is transplanted from one genetically identical donor to the host
        • e.g., transplantation between monozygotic twins
    • allograft
      • tissue is transplanted from one genetically different donor of the same species to the host
        • e.g., kidney transplant
    • xenograft
      • tissue is transplanted from a donor of a different species to the host
        • e.g., porcine heart valve
Transplant Rejection
 
Transplant Rejection
Rejection Type
Pathogenesis
Comments
Hyperacute 
  • Type II hypersensitivity reaction where 
    • pre-existing recipient antibodies attack the donor antigen resulting in
      • complement activation
      • endothelial damage
      • inflammation
      • thrombosis
  • Time
    • minutes to hours
  • Findings
    • capillary thrombosis which
      • prevents graft vascularization
Acute
  • Cellular rejection
    • type IV hypersensitivity reaction where
      • recipient CD8+ T-cells react to donor antigens after activation by antigen presenting cells 
  • Humoral rejection
    • just like in hyperacute rejection; however,
      • the antibodies are formed after transplantation occured
  • Time
    • weeks to months
  • Findings
    • graft vessel vasculitis with
      • lymphocytic infiltrates
Chronic 
  • Type II and IV hypersensitivity reaction secondary to
    • CD4+ T-cells responding to the host's antigen presenting cells
  • Time
    • months to years
  • Findings
    • cytokine secretion after T-cell activation leads to
      • smooth muscle proliferation
      • interstitial fibrosis
      • parenchymal atrophy
Graft-versus-host disease
  • Type IV hypersensitivity reaction secondary to
    • the donor's T-cells attacking the recipient's cells leading to 
      • organ dysfunction
  • Time
    • variable
  • Findings
    • maculopapular rash
    • jaundice
    • diarrhea
    • hepatosplenomegaly
 
Tissue Compatibility Testing
  • ABO blood typing
  • Tissue typing
    • used to see if HLA antigens match and subtypes include
      • HLA-A
      • HLA-B
      • HLA-DR

References



  RATE CONTENT
5.0
AVERAGE 5.0 of 1 RATINGS

Qbank (0 Questions)



Evidence & References Show References




Topic Comments

Subscribe status: