Transplant immunology Flashcards
What is the primary reason for morbidity and mortality in transplants?
The immune response
In a graft, if the MHC molecule doesn’t match, what will happen?
The T cells will recognize the graft as foreign and reject it
CD4+ T cells recognize what?
Antigen + MHC II
CD8+ T cells recognize what?
Antigen + MHC I
What do T cells need to do during education in order to not die?
The need to bind a self peptide and MHC with low avidity
What do T cells need to be activated other than binding something with high avidity?
Costimulatory molecules
Can alloantigen recognition be both direct and indirect?
Yes
What happens due to a hyperacute rejection?
IgM activates the complement cascade, cells die and the blood supply to the graft is clogged and the graft dies
In an acute reaction, what other reaction is also present?
The hyperacute reaction
What is the hyperacute reaction due to?
preexisting alloreactive antibodies. Antibodies then activate the complement cascade
What happens in an acute reaction?
CD8+ T cells are activated and they lyse host target cells. B cells are activated which produce antibodies and the hyperacute response occurs as well
What ultimately causes the rejection of a graft?
the loss of vascular supply to the tissue
What happens in a chronic graft rejection?
Alloreactive T cells produce cytokines that activate parenchymal macrophages. The inflammation can induce growth factor production which induces intimal thickening, thereby closing off the vascular supply
What is the best way to prevent graft rejection?
Prevention- so autologous or syngeneic transplants
What is the purpose of a bone marrow transplant?
Treatment for hematological disease- cancer, immunodeficiency etc. and to restore the immune system destroyed by radiation and chemotherapy