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Flashcards in Transplantation Deck (19):
1

Is HLA matching important for solid organ transplants?

Before cyclosporine and other immune suppressive drugs it was but now it's not considered necessary for many types of organ transplants.

However, MHC matching is still important for HSCT.

2

What is an alloantigen?

genetically determined to be in some individuals of a species

3

When recipient T cells directly see alloantigens on donor APC

Direct recognition
Responsible for acute graft rejection

4

When donor alloantigens are taken up and processed by recipient APC and presented to recipient T cells

Indirect recognition
Responsible for later stages of allograft rejection

5

Autologous

Self

6

Allogeneic

Another individual of the same species

7

Xenogeneic

Different species

8

Chimerism

Mixture of donor and recipient cells

9

Hyperacute rejection

Major barrier to xenotransplantation, occurs within minutes
Complement activation, endothelial damage, inflammation and thrombosis

10

Acute rejection

Can be cellular or humoral in nature; typically occurs within days to weeks in non-immune suppressed individuals or months-years in immune suppressed.
Parenchymal cell damage, interstitial inflammation

11

Chronic rejection

Major cause of graft failure (b/c of improvements in treatment for acute)
Occurs within months to years, vascular changes, interstitial fibrosis, loss of renal parenchyma; get renal ischemia due to loss of glomeruli, interstitial fibrosis and tubular atrophy.
Chronic inflammatory reaction in vessel wall, intimal smooth muscle cell proliferation, vessel occlusion.

12

Name some drugs that help prevent graft rejection.

Cyclosporine
Mycophenolate mofetil
Rapamycin
Corticosteroids
Anti-IL-2 receptor antibody

13

What must a patient undergo before HSCT?

Chemotherapy and/or irradiation to eliminate malignant cells and make space for incoming cells

14

What are minor histocompatibility antigens (miHA)?

Less potent at inducing graft rejection; Cleaved and processed endogenous proteins that occupy the binding groove of MHC class-1 and class-2 molecules
Contain genetic polymorphism-- usually due to SNPs. Can be either MHC class-1 or class-2 restricted.

15

What is the mixed lymphocyte reaction?

A way in culture to measure alloreactivity and mimics what happens in vivo

16

Explain acute GVHD.

Results from reactivity of donor T cells against histocompatibility antigens of the recipient. In acute GVHD, mature T cells in donor graft recognize and react against host antigens, creating a potentially fatal immune response.

17

Explain chronic GVHD.

Late complication (>100d) with autoimmune-like features; thought to be from cytokine and T cell dysregulation.

18

Explain graft vs tumor effect.

Graft contains donor T lymphocytes that are beneficial for recipient because they eliminate residual host T cells or tumors. Develops after recognizing tumor-specific or recipient-specific alloantigens.

19

What is the main difference between direct and indirect alloantigen recognition??

The source of the APC.
Direct the APC is donor.
Indirect the APC Is recipient.