Transplant Immunology

Question 1

Isograft

Answer 1

Identical to self

Question 2

Allograft

Answer 2

Between individuals of the same species

Question 3

Xenograft

Answer 3

Between species

Question 4

First phase of the alloimmune response

Answer 4

Inflammation caused by reperfusion injury and surgical trauma. These things contribute to free radical formation, which causes release of DAMPS, activating complement and TLRs. Innate immune response. Also promote transmigration of T cells.

Question 5

Are MHC’s the targets of transplant immunity?

Answer 5

Yes

Question 6

Alloreactive antibodies

Answer 6

Directed at the polymorphic regions of different MHC’s, can develop through transplant, pregnancy, cross reactivity. Mostly Th1 and IgG.

Question 7

Alloreactive T Cells

Answer 7

Directly recognize donor MHC’s. Occur due to cross reactivity. Created from exposure to viral proteins that look like different MHC’s, can’t be direct, because T cells are already activated.

Question 8

Direct Recognition By Alloreactive T cell

Answer 8

Recipient T cells directly recognize the donor APC, because they have been activated by cross reactivity.

Question 9

Indirect Allorecognition

Answer 9

Recipient APC expresses donor peptide (from their digested HLA’s). Less frequent.

Question 10

Does MHC matching prevent rejection?

Answer 10

No, there are minor histocompatibility proteins

Question 11

Why can’t females respond to male donations?

Answer 11

Y chromosome minor histocompatibility proteins.

Question 12

What do drugs in transplantation do?

Answer 12

They block costimulation and expansion of T cells.

Question 13

CD62 hi CD44 lo T cells, vs CD62 lo CD44 hi T cells

Answer 13

In LN’s, in tissue.

Question 14

Alloantibody effector function

Answer 14

Bind to donor HLA, cause compleent activation, cause microthrombi to form.

Question 15

Hyperacute rejection

Answer 15

caused by ischemia secondary to antibody induced microthrombi

Question 16

T Cell effector mechanisms

Answer 16

Cytokine production, delayed type hypersensitivity. Type IV, cause macrophage activation. Cytotoxicity.

Question 17

How can acute rejection be monitored clinically?

Answer 17

Decrease in kidney function (rise in creatinine), caused by T cells responding via direct pathway.

Question 18

Immunosuppression

Answer 18

is non specific, but primarily targets T cells, not b cells. Can cause kidney fibrosis and susceptibility to infection.

Question 19

Tolerizing Mice Experiment

Answer 19

Fetal mice injected with cells from another strain of mouse didn’t reject the organ of the same mouse.

Question 20

Acquired Transplant Tolerance in humans?

Answer 20

Give BM with graft, block costimulators, expand T regs.