transplant Flashcards
What is the onset of hyperacute transplant rejection?
Within minutes.
What is the pathogenesis of hyperacute rejection?
Pre-existing recipient antibodies react to donor antigens (type II hypersensitivity), activating complement.
What are the features of hyperacute rejection?
Widespread thrombosis of graft vessels (ischemia, fibrinoid necrosis).
Requires graft removal.
What is the onset of acute transplant rejection?
Weeks to months
What is the pathogenesis of acute rejection?
Cellular: CD8+ and/or CD4+ T cells activated against donor MHC (type IV hypersensitivity).
Humoral: Antibodies develop post-transplant (associated with C4d deposition
What are the features of acute rejection?
Vasculitis with dense lymphocytic infiltrate.
Prevent/reverse with immunosuppressants.
What is the onset of chronic transplant rejection?
Months to years.
What is the pathogenesis of chronic rejection?
CD4+ T cells respond to recipient APCs presenting donor peptides (type II and IV hypersensitivity).
Involves both cellular and humoral components.
What are the features of chronic rejection?
Dominated by arteriosclerosis.
Smooth muscle proliferation, atrophy, fibrosis.
What is the pathogenesis of GVHD?
Grafted T cells proliferate in an immunocompromised host and attack host cells (type IV hypersensitivity).
Common in bone marrow/liver transplants (high lymphocyte content)
What are the features of GVHD?
Maculopapular rash, jaundice, diarrhea, hepatosplenomegaly.
what type of HLA is more commonly associated with graft versus host disease ?
HLA- A
HLA- B
HLA- DRwh
what is the treatment for hyperacute transplant rejection ?
the graft must be removed
what iss the treatment for acute transplant rejection ?
immunosuppresannts
how an GVHD be prevented ?
irradiate blood products prior to transfusion
