Transplantation Flashcards
Autograft
One part of body to another
Isograft
Between genetically identical individuals (e.g. monozygotic twins)
Allograft
Between different members of same species
Xenograft
Between members of different species
What is the difference between first- and second-set rejection? Why?
Second-set is accelerated due to presence of a specific memory immune response
Which immune cell is primarily responsible for rejection?
T cell
Where are the MHC genes encoded?
Ch 6
What is the difference between MHC I and MHC II?
MHC I: universally expressed, cytoplasm derived proteins, presents to CD8+ T cells
MHC II: expressed by APCs, EC derived proteins, presents to CD4+ T cells
What is hyperacute rejection and what is the underlying cause?
Rejection within hours
Antibody-mediated due to presence of pre-formed antibodies from previous blood transfusion, pregnancy or transplant
What is acute rejection and what is the underlying cause?
Rejection within weeks
Primary activation of T cells
What is chronic rejection and what is the underlying cause?
Rejection within months or years Cause unclear (antibodies, immune complexes, slow cellular reaction, recurrence of disease)
What are the histological characteristics of acute rejection?
Mononuclear cells invade graft
What are the histological characteristics of chronic rejection?
Intimal fibrosis
Mechanism of action of cyclosporin
Fungal metabolite which inhibits calcineurin to decrease IL-2 transcription, preventing T cell activation
Side effects of cyclosporin
Nephrotoxicity
Mechanism of action of tacrolimus
Binds FK-binding protein which binds calcineurin, prevents transcription of IL-2 and therefore T cell activation
What are the anti-inflammatory and immunosuppressive effects of steroids?
Anti-inflammatory: decreased circulating lymphocytes, neutrophil enzyme release, monocyte activity
Immunosuppressive: decreased lymphocyte proliferation, Ag presentation
Azathioprine
Anti-proliferative drug
Mycophenalate
Anti-proliferative drug
Rapamycin
Anti-proliferative drug
Mechanism of action of anti-proliferative drugs
Inhibits DNA and RNA synthesis (blocks IL-2 production and therefore T cell expansion)
