Transplant Immunology Flashcards
(37 cards)
what is the primary reason for mortality after a transplant ?
immune response to graft leads to rejection
difference b/w orthotopic and heterotopic
orthotopic is transplanting cell/tissue to the same anatomical site
heterotopic is transplanting to a different site
what is the difference b/w and autologous graft, synergeneic graft, and allogenic graft ?
autologous is graft to and from same individual
synergeneic is a graft from genetically identical ind. (twin)
allogenic is from genetically different individual
what complications in transplants are the result of what type of graft ?
allogenic graft
A MHC (a) graft will _______ by an MHC (a) host, whereas a MHC (a) graft will _________ by an MHC (b) host
- Not be rejected
- will be rejected
What is the difference b/w CD8 and CD4 T cells ?
CD8 - cytotoxic t cells, MHC I restricted
CD4 - helper t cells, MHC II restricted
what 3 things do T cells NEED to become effector T cells
- recognize Ag
- MHC activation
- Costimulatory molecule activation
T cells can recognize an alloantigen 2 ways, what are they and how do they differ ?
1 - Direct - T cell receptor engages naked alloantigen
2 - Indirect - APC engulfs an alloantigen, processes it then presents it to T cells
Indirect alloantigen recognition is an example of ?
Cross presentation or cross priming
once a T cell recognizes an alloantigen either directly or indirectly, what occurs ?
T cell becomes activated
What are the 3 ways an allogeneic T cell can lead to graft rejection
1 - hyperacute rejection (w/in minutes to hours)
2 - acute rejection (about 1-2 weeks)
3 - chronic rejection (6 months)
what happens during hyperacute rejection ?
Pre-existing alloreactive Ab are present in recipient
-leads to activation of complement cascade = inflammation = thrombosis formation
what occurs during acute rejection ?
CD8 and CD4 (T cells) become activated leading to
- Cytotoxic t cells lyse target
- helper t cells activate B cells to produce Ab (and same thing happens as hyperacute rejection)
What happens in chronic graft rejection
survive for about 6 months, but eventually blood vessels thicken from increased growth factor production = occlusion of vessels = graft rejecetion
In order from best to least, which types of grafts are least likely to cause rejection
1 - autologous
2 - synergeneic
3 - allogenic
Besides prevention, what is another strategy that can be used to reduce the probablitlity of graft rejection
immunosupression via drugs
There are 4 immunosupression drugs we need to know that prevent graft rejection, what are they ?
Rapamycin
Anti-CD3 monoclonal Ab
Anti-IL-2 receptor Ab
CTLA-4 Ig
How does immunosupression drug rapamycin work
inhibits IL-2 signaling = No T cell proliferation
how does immunosupression drug Anti CD3 monoclonal Ab work ?
depletes T cells by binding to CD3 = phagocytosis
how does immunosupression drug Anti IL-2 receptor Ab work
inhibits IL-2 binding = No T cell proliferation
how does immunosupression drug CTLA-4 Ig work ?
CTLA blocks co-stimulatory activation = no T cell activation (CTLA-4 doesnt allow CD28 to bind to B7)
What are the 2 uses/ reasons for a bone marrow transplant
1 - treatment of hematological disesase
2 - restore an immune system destroyed by chemo/radiation
what is the name of the disease, when the graft attacks the host in a bone marrow transplant ?
graft versus host disease
-hapens b/c trying to introduce a completely new immune system
cells of what part of the immune system are Ag specific
adaptive immune system
