Tissue Graft Rejection

Question 1

Autograft

Answer 1

graft from same individual, no immune response

Question 2

Isograft

Answer 2

graft from genetically identical individual (twin, lab mice), no immune response

Question 3

Allograft

Answer 3

From genetically different individual of the same species

strong immune response if different MHC

Question 4

Xenograft

Answer 4

Different species providing graft. Rapid intense graft rejection in hours

Question 5

Allograft antigens

Answer 5

MHC, blood group glycoproteins, endogenous antigens on MHC I

Question 6

CD8 T cell role in graft destruction

Answer 6

destroy vascular endothelium, stop blood flow to graft

Question 7

CD4 T cell role in graft destruction

Answer 7

Release of cytotoxic cytokines (TNF-alpha), apoptosis in endothelial cells

Question 8

Macrophage role in graft destruction

Answer 8

Pro-inflammatory cytokine release, impair graft function and intensity T cell response

Question 9

Hyperacute rejection

Answer 9

due to pre-existing antibodies. occurs up to 48 hours after graft

Question 10

Acute rejection

Answer 10

Donor APCs present to host T cells, T cells recognize MHC as foreign and mount attack, thrombosis and blood flow to graft ends

Question 11

Chronic rejection

Answer 11

Indirect presentation. Response mounted only against donor tissue antigens.

Question 12

Immunosuppression mechanisms

Answer 12

Inhibition of T cell signalling pathways, kill proliferating T cells, function-blocking/depleting anti-lymphocyte antibodies, costimulatory blockade drugs, targeting alloantibodies and alloreactive b cells, anti-inflammatory drugs

Question 13

Graft versus host disease

Answer 13

GVHD is due to grafted T cells from bone marrow transplant react to host cells. May be due to immunosuppression by irradiation