Transplant

Question 1

What cells from the recipient are responsible for rejection of a transplant?

Answer 1

T cells

Question 2

When a BM transplant takes place, what cells attack the recipient? Why? What is this called?

Answer 2

Donor’s T cells, because host doesn’t have their own immune system- GVHD

Question 3

What is one of the reasons that MHC proteins are so highly polymorphic?

Answer 3

Might prevent accidental transplant (prevent one animal from transmitted a tumor into another)

Question 4

What is a MHC?

Answer 4

Major Histocompatibility Complex; a set of three genes that produce the proteins seen on cells

Question 5

What are blood antigens?

Answer 5

Polysaccharides on the surface of RBC

Question 6

Does the body naturally make Ab against blood antigens not present on RBCs? to D Ag?

Answer 6

Naturally to blood antigens not present; only makes Ab to D Ag following exposure (such as during pregnancy)

Question 7

What causes a hyperacute rejection?

Answer 7

When preformed antibodies from the recipient react with the host

Question 8

What are examples of hyperacute rejection?

Answer 8

Mismatching blood type; if had a previous transfusion/transplant then could already have antibodies to other MHC Ag; if had a baby then could have Ab to the MHC from the child

Question 9

How quickly does a hyperacute reaction take place?

Answer 9

Hours

Question 10

During hyperacute rejection where do the recipient Ab bind on the transplanted organ?

Answer 10

RBC Ag or MHC within the vascular epithelium

Question 11

What is the test called to see if a patient has antibodies against a given HLA?

Answer 11

Panel Reactive Ab Test

Question 12

How does a panel reactive Ab test work?

Answer 12

Take the serum from a recipient and put it on leukocytes from different people and therefore people with different HLA

Question 13

What cells are involved in acute rejection?

Answer 13

T cells

Question 14

How long does acute rejection take?

Answer 14

Days to weeks

Question 15

What are the two possible mechanisms for acute rejection?

Answer 15

1. Donor cells expressing MHC Class II react with the host immune system (APC within host present)
2. Donor cells get expressed by recipient APC

Question 16

What cells are involved in chronic rejection?

Answer 16

Ab to the transplanted MHC/ minor transplanted Ag- usually Ab to MHC Class I

Question 17

How long does it take for a chronic rejection to occur?

Answer 17

Months or years

Question 18

What is alloreactivity?

Answer 18

Reacting to a different individual within the same species

Question 19

What are the steps in finding a potential transplant match?

Answer 19

Match blood type first, then HLA I and II, find match on computer, cross match on all potential candidates (recipient serum against candidates cells)

Question 20

What is more important in terms of matching prior to transplantation? HLA I or HLA II?

Answer 20

HLA I

Question 21

What happens during a mixed lymphocyte reaction?

Answer 21

Take graft lymphocytes and irradiate them so that they can’t proliferate, then add the host lymphocyte and look for any reaction

Question 22

What testing is done monthly following transplantation in an attempt to avoid rejection?

Answer 22

Screen for anti-HLA Class I

Question 23

How do corticosteroids work?

Answer 23

Knockout T cells

Question 24

How do cytotoxic drugs work?

Answer 24

Interfere with DNA synthesis

Question 25

How do cyclosporin and FK506 work?

Answer 25

Inhibit the signaling used by T cells

Question 26

What are antilymphocyte globulins? Where do they come from?

Answer 26

Ab directed against T cells- made from animals

Question 27

With what cancers might you need a BM transplant? Why?

Answer 27

Leukemia/lymphoma; treat with chemo to get rid of the cancer, but knockout the healthy BM at the same time

Question 28

What happens during GVHD?

Answer 28

Grafts mature T cells attack the host’s cells

Question 29

What reduces the severity of GVHD?

Answer 29

A better MHC match or removing T cells from the graft

Question 30

When might a GVHD be helpful?

Answer 30

Appears to be beneficial in engraftment; also might help kill residual tumor in leukemic patients