L20 Immune mediated disease 4 transplants

Question 1

Name the types of transplants

Answer 1

AAIX
Autograft
Allograft- bt members of the same species
Isograft- bt genetically identical individuals
Xenograft-bt species

Question 2

Allograft

Answer 2

bt members of the same species

Question 3

Isograft

Answer 3

bt genetically identical individuals

Question 4

Xenograft

Answer 4

bt species

Question 5

Describe DIRECT T-cell mediated graft rejection

Answer 5

• T cells of the transplant recipient recognize allogeneic (donor) MHC molecules on the surface of APCs in the graft 


•	CD8+ T cells recognize class I MHC molecules and differentiate into active CTLs 


•	CD4+ helper T cells recognize allogeneic class II molecules and proliferate and differentiate into TH1

Question 6

CD8+ T cells in direct T-cell mediated graft rejection

Answer 6

•	CTLs 

•	Directly kill cells that express donor class I MHC 

•	Parenchymal cells 

•	Endothelial cells 
−	Thrombosis 

−	Graft ischemia

Question 7

CD4+ helper T cells in direct T-cell mediated graft rejection

Answer 7

• CD4+TH1 cells activate a Delayed Type Hypersensitivity 

• increased vascular permeability and local accumulation of mononuclear cells (lymphocytes and macrophages) 

• graft injury by the activated macrophages 


Question 8

Describe INDIRECT T-cell mediated graft rejection

Answer 8

• recipient T lymphocytes recognize MHC antigens of the graft donor after they are presented by the recipient’s own APCs 

• CD4+ T cells that enter the graft and recognize graft antigens 

• delayed hypersensitivity type of reaction

Question 9

Name the types of organ rejection

Answer 9

HAC
Hyperacute mins-hours
Acute cellular/vascaular varies
Chronic months-years

Question 10

Hyperacute rejection

Answer 10

Minutes to hours 

Antibody mediated activation of complement 
−	Presensitized host 

−	Antibody and c’ mediated 

−	Endothelial injury 

−	Thrombosis 

−	Fibrinoid necrosis 

−	Ischemic necrosis 


Question 11

Acute cell mediated rejection

Answer 11

− Interstitial CD4+, CD8+, macrophage infiltrate 

− Mononuclear infiltrates found in glomeruli and peritubule capillaries 

− Edema 

− Hemorrhage 

− Focal tubular necrosis 

− Endotheliitis: inflammation of inflammation cells 


Question 12

Acute humoral rejection

Answer 12

•	Endotheliitis 

•	Endothelial cell necrosis 

−	C’, inflammation, ADCC 
•	Neutrophilic infiltrate 

•	Deposition of antibody, complement, fibrin 

•	Focal thrombosis 


Question 13

Chronic rejection

Answer 13

Months to years 

•	Vascular changes (smooth muscle proliferation) arteries and arterioles 

•	Interstitial fibrosis 

•	Loss of parenchyma 

•	Compromise vascular perfusion 

•	Renal ischemia