Transplant Reactions

Original article by Tom Leach | Last updated on 7/6/2014
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Hyperacute Rejection

  • Occurs within minutes (to hours) – so quick that the surgeon is sometimes able to visualise characteristic changes whilst sill performing the anastomosis of blood vessels.
  • There is rapid agglutination (clumping together of blood cells), which is particularly risky for renal transplant patients. The reaction seen is the same as a blood transfusion reaction.
  • Due to preformed antibodies already present in the recipient at the time of transplant
    • Most commonly due to mismatched blood group – so risk can be minimised if blood groups are matched. 
 

Treatment

  • There is no treatment
  • The transplanted organ must be removed immediately to prevent a dangerous systemic inflammatory response
 

Acute Rejection

  • Can occur from 1 week – 3 months after transplantation
    • Rarely it can occur months or years later
  • It can be successfully treated
  • If recurrent, it can become a chronic rejection.
 

Pathology

In some senses, a varying degree of acute rejection occurs in all transplants. It is due to HLA incompatability – a degree of which exists between all individuals (except identical twins). there is a T-cell mediated reaction against the transplanted tissues, which results in endovascular damage, as well as lysis and necrosis of the transplanted tissue. The kidneys and liver are at particular risk.
  • Accelerated acute rejection – the T cells are re-activated
    • Reaction occurs within days
  • Acute rejection – the T cells are sensitised and subsequently activated
    • Reactions occurs within days-weeks
 

Diagnosis

  • Usually require tissue biopsy, which reveals:
    • T-cell infiltration of the transplanted tissue
    • Structural damage of the transplanted tissue
    • Vascular damage of the transplanted tissue
 

Management

  • Can be managed with immunosuppressant agents e.g:
    • Cyclosporin
    • Azathioprine
    • Steroids
    • Anti-monoclonal antibodies (e.g. infliximab, Rituximab)
  •  Plasma exchange (plasmapheresis) is also an option
  • Some centres will use induction regime of plasma exchange or monoclonal antibodies to reduce the chance of acute rejection in high risk patients

Chronic Rejection

This a controversial topic. It is thought chronic rejection is an antibody mediated process that occurs after months or years, and results in vascular damage.
  • Lung transplant
  • Has the worse outcomes (mean survival about 5 years), as a result of chronic rejection
  • The rejection results in bronchiolitis obliterans,  and is characterised by progressive airways obstruction, causing SOB and dry cough
 

Management

  • Chronic rejection is a progressive, irreversible process
  • The only curative treatment is re-transplant