MHC and transplanatation

Question 1

In what types of cells is blood group substance found

Answer 1

all vascular endothelial cells.

Question 2

what 2 types of isoagglutinins do all individuals have

Answer 2

anti A and anti B

Question 3

what are isoagglutinins

Answer 3

Antibodies produced by an individual that cause agglutination of red blood cells in other individuals.

Question 4

what happens when a donor is mismatched for the second time

Answer 4

necrosis is much faster.
• This is because the immune system has formed a memory
• 2nd response is more vigorous.

Question 5

What is MHC

Answer 5

set of genes found in all vertebrate species.

Question 6

What are the key roles of MHC

Answer 6

immune function- present ‘self’ and ‘nonself’ antigens for inspection by T cell antigen receptors.
disease susceptibility
reproductive success.

Question 7

what chromosome is MHC found on

Answer 7

6 (short arm)

Question 8

how many classes of MHC are there

Answer 8

3

Question 9

which classes of MHC are involved in transplant

Answer 9

class I and class II (encode antigens)

Question 10

what cell are class I expressed on

Answer 10

all nucleated cells.

Question 11

What cells are class II antigens expressed on

Answer 11

B lymphocytes and expression can be indued on T lymphocytes

Question 12

what type of biochemical molecules are MHC/HLA

Answer 12

glycoproteins.

Question 13

How is MHC inherited

Answer 13

mendelian inheritance
each individual inherits 2 antigens at a given locus.
co-dominant expression. All inherited antigens are displayed on the cell surface.

Question 14

what type os blood cell has lots of HLA’a

Answer 14

WBC

Question 15

Is HLA highly polymorphic

Answer 15

Yes large number of allelic variants at each locus.

Question 16

why is the advantage of having so many types of HLA

Answer 16

survival advantage
– as everyone in the population will have developed resistance and immunity against certain pathogens, overall as a population we have immense immunity to lots of pathogens.

Question 17

How do we determine different allelic forms of HLA which can form polymorphisms

Answer 17

use primers

Question 18

Is HLA part of the adaptive or complement immune system

Answer 18

adaptive

Question 19

What is direct recognition

Answer 19

happens immediately after transplant.
not typical body process.
T cells get through due to damage of capillary wall from surgery and stress and bind to graft.

Question 20

What is indirect recognition

Answer 20

normal process.
APC moves into tissue and is presented with graft peptides which it then processes and presents
migrates to lymph nodes where it can present it to T cells, which migrate to the graft

Question 21

What is semidirection recognition.

Answer 21

• Recipient APc move in to tissue
• Binds with donor APC
• Migration of this new APC to lymph nodes where it will present to T cells.

Question 22

define sensitization

Answer 22

Any event which elicits an HLA directed immune response
• Pregnancy- foetus is allograft
• Blood transfusion- contain WBC which have HLA.
• Transplantation- HLA or the donor

Question 23

what methods are used to prevent sensitisation

Answer 23

• Serum screening- determines patients and donors HLA profile to see if they match
• Cross matching- checks recipients’ serum against donors.

Question 24

How does cross matching take place

Answer 24

• Donor T lymphocyte with HLA
• Recipient serum added which many contain antibodies against the HLA.
• Florescence second antibody is used to see whether the antibody- HLA complex has formed
• This is read through a detector.

Question 25

when does a hyper acute rejection occur

Answer 25

severely mismatched HLA

Question 26

What happens in hyper acute rejection

Answer 26

•	Antibodies in the recipient bind to endothelial cells of the transplant as they class it as foreign
•	This activates the coagulation cascade
–	Activate clotting cascade
–	Activate complement
–	Transplant becomes leaky and necrotic