Hyperacute Transplant Rejection

Summary

Hyperacute Rejection is a type of transplant rejection that happens immediately within minutes of receiving a new organ transplant. Hyperacute rejection is caused by pre-existing antibodies against the graft. These are mainly IgG antibodies targeted against donor ABO or HLA antigens. Since hyperacute rejection is an unwanted immune reaction mediated by antibodies, it is technically a type 2 hypersensitivity reaction. On pathology, hyperacute rejection is characterized by widespread thrombosis or formation of blood clots, which ultimately cuts off blood supply to the transplanted organ. There is no treatment for hyperacute rejection, and the graft must be removed. 

Key Points

• Hyperacute Rejection
  • Occurs minutes after transplant (hyperacute)
  • Pre-existing recipient antibodies vs. graft
    • Usually target ABO or HLA antigens of graft
    • Antibodies cause Classical Complement Activation, which leads to damage
    • Example of Type II Hypersensitivity Reaction
  • Widespread thrombosis of graft vessels
    • Results in ischemia and necrosis of the transplanted organ
  • No treatment (irreversible)
    • Graft must be removed