Transplantation Flashcards
(22 cards)
What is an allograft (most common type) and what must you do to prevent rejection
Transplant from genetically non-identical member of same species
Have to tissue match to prevent rejection
What is an isograft
Transplant from identical twin
Still requires immunosuppression as exposed to different antigens throughout life so different Ab’s
What is an autograft
Transplant between different sites on same organism
Skin graft or buccal urethrostomy
What is an xenograft
Transplant from different species e.g. heart valves
What will an unmodified xenograft lead to
Hyperacute rejection as humans have natural IgM anti swine Ab and pigs don’t have HLA
How do you prevent rejection in xenograft
Remove IGM
Genetically modify pigs
Humanised transgenic pigs
What are privelledged sites
Little blood or lymphatic supply e.g. cornea
No tissue matching or immune suppression needed
What are complications of transplantation
Rejection Bleeding Wound infection Vacular thrombosis New onset DM Infections Electrolyte / fluid disturbance Malignancy - post transplant lymphoma / SCC Drug SE Recurrence of original disease
What causes rejection
ABO or HLA incompatible
Preformed immunity from previous transplant / pregnancy / blood transfusion (sensitisation)
Failed immunosuppression or non-compliance = most common
Infections
Environment
How do you prevent rejection
What is most important
ABO matching - need exact match or get immediate reaction
Tissue typing - HLA doesn’t need to be perfect but ensures longer graft
HLA Class 2 most important - HLA-DR
HLA - A and B of class 1 also important
Prophylactic immunosuppression
What is given prophylactic as immunosuppression as long as transplant in
Corticosteroid
Tacrolimus - calcineurin inhibitor that blocks IL-2 which is released in any inflammation
MMF.- anti-proliferative of lymphocytes
What happens in hyperacute rejection
Organ won’t perfuse
Usually due to ABO / HLA mismatch - preformed Ab in blood so quick
Activates innate immune so hard to stop
What increases risk of hyperacute
Previous transplant
Pregnancy
Blood transfusion
What causes acute rejection <6 months
Cell + Ab mediated (Innate)
T cell recognise allo-MHC and attack
Inflammation and parenchymal damage of organ
Can lead to chronic
What is the treatment for acute rejection
Aggressive immunosuppression
What is chronic rejection
Most common cause >6 months Chronic inflammation to alloantigens Ab mediated with other innate components Can't fix once started
How do you treat rejection
IV steroid and oral corticosteroid in high dose
Anti-thymocyte globulin
IV Ig
Plasma exchanhe
What is required in GVHD
Immunocompotent cells in graft
Immunocompromised host
HLA mismatch between donor and recipient
How do you prevent GVHD
Donor T cell depletion / leucocyte depletion
Matching
What are types of donation
Living - related, unrelated, altruistic
Deceased - brain death (DBD), cadaveric death (DCD)
What does GVHD cause
Catastrophic reaction as graft destroys ever tissue in body
What is best type of donation
Living related
