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POD Exam II > Transplantation > Flashcards

Flashcards in Transplantation Deck (10):
1

Autograft:

From one part of the body to another.

2

Isograft:

Between genetically identical individuals.

3

Allograft:

Between different members of the same species.

4

Xenograft:

Between members of different species.

5

Direct recognition:

T cells may recognize allogeneic MHC molecules on the graft.
- Displayed by donor dendritic cells in graft.
- May be processed and presented by host dendritic cells.
- T cells become activated.

6

Indirect recognition:

If graft cells are ingested by recipient dendritic cells.
- Donor alloantigens are presented by self MHC molecules on recipient APCs.

7

Hyperacute rejection:

- Occurs within minutes or hours after transplant; surgeon can see this occur.
- Antigen-antibody reaction; pre-formed antibodies.
- Thrombotic occlusions of capillaries.
- Fibrinoid occlusion of arterial walls.
- Kidney cortex get infarction with necrosis.
- Must be removed.

8

Acute rejection:

- Occurs in days after transplant or much later if patient stops immunosuppression.
- Both humoral and cellular mechanisms.
- Can respond to increased immunosuppression.
- Extensive mononuclear infiltrate.
- Endothelitis: CD8 cells invade and damage vascular endothelium.
- Called tubulointerstitial rejection

9

Chronic rejection:

- Occurs months to years.
- See slow rise in creatinine.
- Vessels - dense intimal fibrosis that occludes the vessel lumen.
- Interstitial fibrosis.
- Tubular atrophy with loss of renal parenchyma.
- Glomerular changes: chronic transplant glomerulopathy - duplication of basement membrane.

10

Graft-versus host disease:

- Caused by the reaction of *grafted* T cells with alloantigens of the recipient.
- Recipient is immunocompromised; unable to reject allogeneic cells in the graft.
- Develops when significant numbers of T cells are transplanted.
- Often directed to minor histocompatibility antigens.
- Target organs are skin, liver and intestine.