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Flashcards in Immune aspects of kidney transplant Deck (41)
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1

Do transplantations between non-identical twins show rejection?

No - share bone marrow in utero

2

What does HLA stand for?

Human leukocyte antigen

3

What does HLA do?

Responsible for the activation of the immune response

Stimulate T and B cell responses

4

What class of HLA are expressed on all nucleated somatic cells?

Class I HLA-B

5

What happens in organ rejection?

HLA recognises proteins on the transplanted organ as non-self and attacks it by mounting an immune response

6

What are 3 types of HLA molecules?

HLA-A, -B and -DR

7

What do -A, -B and -DR represent on HLA molecules?

Important alleles

8

Where are HLA-DR found?

On immune cells

9

How many alleles code for each HLA subtype (-A, -B, -DR)?

2 alleles

10

How do we use the HLA molecule to determine the compatibility between potential donor and recipient?

Compare the alleles that make up the HLA subtypes between the recipient and donor

For example, for the HLA-A

Donor = two alleles that code for this molecule are HLA-A1 and HLA-A1

Recipient = two alleles that code for this molecule are HLA-A1 and HLA-A2

Matching = 1

Do the same for HLA-B and HLA-DR

Complete match = 0, 0, 0
Complete mismatch= 2, 2, 2

11

What is the relationship between HLA and MHC?

HLA = MHC in humans

12

What determines the alleles that code for the HLA subtypes?

Alleles are inherited from your parents

13

What is the role of HLA-DR?

Binds to specialised antigen presenting cells

Stimulates activation and proliferation of T cells

Releases cytokines which stimulate the immune response

14

What effect does HLA mismatching have on success of transplantation?

The more different the HLA - the greater the immune response - the more immunosuppression is needed - the higher the probability of rejection of the graft

15

What is transplant rejection?

Process by which the immune response attacks the donor organs

16

What are the three types of transplant rejection?

1. Hyperacute

2. Acute

3. Chronic

17

What is the timeline of hyperacute transplant rejection?

Minutes - hours

18

Why does hyperacute transplant rejection occur?

Pre formed antibodies are present in the body

Due to the antibodies being exposed to ANY foreign HLA in the past

Exposure to foreign HLA happens in

Pregnancy
Blood transfusion
Previous transplantation

19

Describe a method to test for preformed antibodies in a host

1. Take serum from the recipient in which there would be preformed antibodies

2. Mix serum with donor cells

3. Add complement to lyse the antibodies stuck to the donor cells

4. Detect whether these are preformed antibodies

20

What do preformed antibodies attack?

Donor HLA antigens

Blood group antigens

21

How do preformed antibodies lead to transplant rejection?

Preformed antigens stick to endothelial cells

Trigger complement and clot formation

Form inflammation within the vessel

Occlude the transplanted organ blood supply = ischaemia

22

What is the timeline of acute transplant rejection?

Days - weeks

23

What leads to acute transplant rejection?

Can be

Cell-mediated -> T cells, macrophages and monocytes

Antibody mediated -> bind to HLA molecules or other antigens present in the blood vessels

24

What leads to organ rejection in acute transplant rejection?

Triggering of the complement cascade acts as an amplification signal of inflammation and coagulation

Eventually leads to organ rejection

25

What is the timeline of chronic transplant rejection?

Months - years

26

What mechanisms leads to chronic transplant rejection?

Cellular and humoral rejection

T cell mediated response to donor cells

Complement activation

27

Very little can be done to slow down chronic transplant rejection

TRUE or FALSE

True

28

What percentage of grafts are lost due to chronic transplant rejection?

50%

29

What are methods by which we have managed to increase transplant donations?

Paired donation

Desensitisation crossmatch positive

Plasmapheresis

30

What is paired donation?

If living donors are not suitable for the recipient - check to see if they are suitable for another recipient

Non compatible donors can ve switched between the two recipients