2.9 immuno

Question 0

Kidney allograft rejection steps

Answer 0

Kidney’s dendritic cells migrate to spleen where they activate effector T cells
Effector T cells migrate to graft via blood
Effector T cells destroy kidney graft

Question 1

Skin graft - what happens in rejection

Answer 1

Skin graft has langerhans cells
Langerhans cells migrate to lymph node where they activate host effector cells
Effector cells migrate to graft via blood
Effector cells destroy graft

Question 2

Characteristics of acute organ rejection

Answer 2

Swelling
Hemorrhage
Necrotic tissue

Question 3

What drugs are used to prevent graft rejection

Answer 3

Prednisone (corticosteroid)
Cyclosporin
FK506 / tacrolimus
Rapamycin (prevents IL2 signaling)

Question 4

Mechanism of steroid action

Answer 4

Steroid goes thru plasma membrane and binds receptor in cytosol
Binding displaces hsp90 dimer from receptor, so now DNA binding site exposed
Receptor+steroid enters nucleus and binds specific DNA sequences in promoter region
Increase in IkBa which decreases NFkB immune activation

Question 5

Mechanism of CsA and tacrolimus

Answer 5

CsA binds cyclophilin, tacrolimus binds FKBP
These bind to calcineurin and prevent it from activating NFAT
Now NFAT can’t go to nucleus and activate AP1, which forms a transc factor of IL2 gene for T cell clonal expansion

Question 6

Graft vs host disease steps

Answer 6

Bone marrow transplant has donor T cells
Donor T cells blood to second lymphoid tissues
Donor T cells interact with host dendritic cells and proliferate
Differentiated CD4 and 8 T cells enter tissues and cause damage

Question 7

Acute rejection uses

Answer 7

Direct recognition

Question 8

Chronic rejection uses

Answer 8

Indirect recognition

Question 9

Hyper acute graft rejection

Answer 9

When recipient already has antibodies against donor antigens, a rapid Ab mediated rejection occurs

Prevent by cross matching blood to detect Ab against donor Ag

Question 10

Fetus might be well tolerated by mother because of

Answer 10

Trophoblast cells of placenta lack MHC expression

Secrete Th2 inducing cytokines (TGFb, IL4, IL10) favors T cell tolerance

Question 11

Mixed lymphocyte reaction

Answer 11

Donor APC
Host T cell
3H-T

If T cells proliferate (can see through 3H-T), not compatible

Depends on MHC class II

Question 12

51Cr-release assay

Answer 12

Cytotoxic T cell from host
Donor cells labeled with 51Cr

Detect increase in 51Cr from T cell killing donor cell

Depends in MHC I