Transplant Flashcards
What is transplantation?
Replacement of tissues or organ that have undergone irreversible pathological damage which threatens the patients life or, to a significant degree, considerably hampers their quality of life
What are the types of graft in transplant?
Autograft- self
Isograft- identical twin
Allograft- one person to another
Xenograft- different species
What are the types of deceased donor?
Brain dead
Cadaveric dead
What are the major compatibility makers?
HLA
ABO
What is HLA1?
Found in all cells and allow recognition as self
Recognise by cytotoxic T cells
What is HLA2
Only in antigen presenting cells
Most important in rejection
T helper cells recognise
What type of reaction with an ABO mismatch cause?
Hyperacute
What are privileged sites?
Tissues with little immunological tissue, so don’t require tissue matching or immune suppression
What is an example of a privileged site?
Eyes
What is rejection?
Transplanted tissue is rejected by recipients immune system, which destroys transplanted tissue
What are the causes of rejection?
ABO or HLA incompatible
Pre-formed immunity
Faied immunosuppression
Infections/environmental triggers
What are the types of rejection?
Immediate
Acute
Chronic
What is immediate rejection?
Seconds to minutes
Innate immune response caused by ABO or HLA incompatibility
What is the process of immediate rejection?
Complement activation damages blood vessels
Inflammation and thrombosis
What ar the risk factors for immediate rejection?
Previous transplant
Previous pregnancies
Blood transfusions
What is acute rejection?
Usually days, up to 6 months
Innate and adaptive immune system
What is the process of acute rejection?
Sensitisation phase
cellular infiltration of graft by cytotoxic T cells, B cells, NK cells and macrophages
Endothelial inflammation and parenchymal damage
What is the sensitisation phase of acute rejection?
Recognition of allontigens by CD4 and CD8
APC reaction as T cell receptors react with APCs via MHC
Costimulation
What is chronic rejection?
Most common cause of rejection
>6 months
Antibody mediated with other innate components
What is the process of chronic rejection?
Myointimal proliferation in arteries- cytokines and antibodies cause a chronic inflammatory process that proliferates cell walls to protect themselves, which blocks off blood flow and leads to ischaemia and fibrosis
How is rejection prevented?
ABO matching
Tissue typing
Prophylactic immune suppression
What immune suppression is given post transplant?
Corticosteroids
Calcineurin inhibitors
Anti-proliferatives
What is the treatment of rejection?
Corticosteroids- IV then oral, high dose
Anti-thymocyte globulin
Plasma exchange- esp goof for antibody mediated
What are the possible complications of transplant?
Rejection Infection Neoplasia Drug side effects Recurrence of original disease Surgical complications Ethical
What is graft vs host disease?
Immune cells from donor tissue attack the recipients tissues
What factors are involved in graft vs host disease?
Immunocompetent graft
Immunocompromised host
HLA mismatch
