Transplant Immunology Flashcards
Hypersensitivity type I
Allergy/anaphylactic
IgE
Ab mediated
Hypersensitivity type II
Cells/cytotoxic
IgG, IgM
Ab mediated
Hypersensitivity type III
Immune complex
IgG, IgM
Ab mediated
Hypersensitivity type IV
Delayed type hypersensitivity
T cell
Cell mediated
What T cells are most important in type 4 HS
CD8 and TH2
Self tissue transferred from one body site to another in the same individual
Autografts
Tissue transferred between genetically identical individuals
Isograft
Tissue transferred between genetically different members of the same species
Allograft
What is the most common classification of grafts
Allograft
Tissue transferred between different species
Xenografts
Doesn’t work well
Transplanted tissue is rejected by the host
Host vs graft disease
Host is attacked by transplanted T cells
Graft vs Host disease
What is the typical rejection called
Host vs graft disease
Who do we typically see graft vs host disease in
Immunocompromised people.
T cells from bone marrow can attach newborn after transplant because they are immunocompromised
Where is HLA located
Short arm of chromosome 6
What are the most important HLA for type I
HLA-A, HLA-B
What is the most important HLA type for type II
HLA-DR
What is the most common organ transplant
Blood
What is the second most common organ transplant?
Cornea. Don’t have to worry about HLA typing because they don’t have MHC. Don’t need to treat them with immunosuppressant like all other tissues
What is critical in transplant rejection
T cells
What happens to rate of rejection after someone has already had a rejected transplant in the past?
They reject much faster
Antibodies to HLA can play a big role in rejection, but _________ play biggest role
T cells
Long survival of allografts in children with
Thymus deficiency, tells us that T cells are important in rejections
What T cells are involved in graft rejection
CD4 and CD8
Blocking CD8 alone, graft rejected in how many days
15 days
How many days to reject hen just blocking CD4 alone
30 days
How many days does it take to reject graft when blocking CD8 and CD4
60 days
Which T cell is most important in graft rejection
CD4, but CD8 does play some role
What do you have to make sure of before giving someone a transplant
Make sure they are ABO compatible
What are the two stages of graft rejection
Sensitization stage
Effector stage
What stage of graft rejection has antigen reactive lymphocytes activated by graft alloantigens
Sensitization stage
What stage of graft rejection is there immune destruction of the graft
Effector stage
What T cells recognize alloantigens
CD4 and CD8
Cells that recognize MHC I
CD8
Cells that recognize MHCII
CD4
Donor and recipient APCs migrate from graft to
Block sensitization to prevent rejections
What happens in the sensitization stage of graft rejection
- CD4 and CD8 T cells recognize alloantigens
- donor and recipient APCs migrate from graft to block sensitation to prevent rejection
- stimulate activation of T lymphocytes
Effector stage
- Ab mediated
- cell mediated
- cytokines released
What does IL-2 do in graft rejection
Promotes T cell proliferation
What does IFN-y do in graft rejection
Promotes DTH response, promotes influx of macrophages.
UPREGULATES MHCI AND MHCII
TYPE I HS
What does TNF-B (LT-a) do in graft rejection
Is cytotoxic to graft cells
What type of HS reaction are the cytokines in the effector stage of graft rejection
Type I
What for IFN-y do in graft rejection
upregulates MHC I and MHC II so it can check out the graft and tell it to “reveal itself”
What does the TNF-a do in graft rejection
Waits for it to reveal itself so it can kill it (MHCI)
What are the types of rejections
- hyperacute rejection
- acute rejection
- chronic rejection
What type of HS reaction is hyperacute rejection
Type II (Ab mediated)
What type of HY reaction is acute rejection
Type 4 (cell mediated)
What type of HS reaction is chronic rejection?
Both type II and IV (Ab mediated and cell mediated)
Hyperacute rejection
Minutes to days
Acute rejection
Weeks up to 6 months
Chronic rejection
6 months or longer
What does hyperacute rejection occur due to
Preexisting host Ab to HLA (woman who has had multiple births will have this
Someone who has had previous blood transfusions is susceptible to what?
Hyperacute rejection, due to residual WBC in blood
Who is predisposed to hyperacute rejection
- previous blood transfusion
- multiple pregnancy
- previous transplants
What happens once hyperacute rejection happens
- fever and anaphylactic reaction
- infilatration of neutrophils
- cap blood clotting
Hyperacute rejection is due to what
Preformed AB to HLA
What is acute rejection caused by
Infiltration of grafts by mononuclear cells (CD4 cells)
Involves T cell mediated reactions (HS type 4)
What does chronic rejection include
Humor and cell mediated responses (2 nad 4)
What is IDed in donor organs before transplant
HLAs, also IDed in recipient tissue
What does microcytotoxicity test for
Test for HLA
Add Ab from recipients to donor cells
-if Ab binds, will kill cell
Look at the blue circles and see whihc ones match up the best to the recipient ones
Which match is more important in degree of match?
MHC II
What are the most important HLAs in MHC I
A and B
What is the most important HLA for MHC II
DR
Compatibility is determined by mixing killed donor lymphocytes (MHC) with recipient lymphocytes
Mixed lymph response (MLR)
What is proliferation in MLR measure by
Uptake of tritiated thymidine
Whe looking at MLR, what can you tell
Lower number=Celsius are happy with transplant
Higher number=host not happy with transplant (they are ‘hot and angry’)
What are the 3 processes of immunosuppression therapy
- surgical (remove)
- irradiation (radiate)
- drugs (slow down rejection time)
What kind of immunosuppression therapy does a corneal transplant need
None
Transplant complications
- infection
- malignancy
- tissue rejection
What is the number one transplant
Blood transfusion
What is the second most common transplant
Cornea
