Transplant Immunology

Question 0

Isograft

Answer 0

syngraft

transfer of tissue between identical twins

Question 1

autograft

Answer 1

transfer of one’s own tissue from one site to another

burn victims, coronary bypass

Question 2

Allograft

Answer 2

transfer of tissue between genetically different members of the same species

Question 3

Xenograft

Answer 3

heterograft
graft between members of different species
baboon heart

Question 4

Orthotopic transplant

Answer 4

transplant into an anatomical normal recipient site

heart into chest

Question 5

Heterotopic transplant

Answer 5

transplant into anatomically abnormal site

kidney into iliac fossa

Question 6

what is transplant rejection due to?

Answer 6

recognition of foreign MHC antigens by T cells activation

Question 7

What two transplants have low or no concern for rejection?

Answer 7

Corneas are not vascularized so can even transplant between unmatched individuals
RBC express no MHC but recipients still need to be matched for ABO and Rh blood types
Pig valves are not vascularized

Question 8

what is a lifelong requirement of transplant recipients?

Answer 8

They will have to be immunosuppressed to prevent graft rejection

Question 9

Agglutinogens

Answer 9

Antigens on the surface of RBCs that allow the immune system to recognize cell as self

Question 10

Agglutinins

Answer 10

antibodies in the plasma

Question 11

What does the H gene code for?

Answer 11

an enzyme that adds sugar fucose to the terminal sugar of a precursor substance
H antigen is the foundation upon which A and B antigens are built

Question 12

A gene codes for enzyme (transferase)

Answer 12

that adds N-acetylgalactosamine to the terminal sugar of the H antigen
N-acetylgalactosaminyltransferase

Question 13

B gene codes for an enzyme that adds

Answer 13

D - galactose to the terminal sugar of the H antigen

D-galactosyltransferase

Question 14

forward typing

Answer 14

determines antigens on patients or donor’s blood

cells are tested with antisera reagents

Question 15

reverse typing

Answer 15

determines antibodies in patients or donor serum or plasma
serum tested with reagent A cells and B cells
Reverse grouping is also known as back typing or serum confirmation

Question 16

HLA forms part of

Answer 16

MHC

Question 17

HLA found on what chromosome?

Answer 17

short arm of chromosome 6

Question 18

What cells are MHC 1 found on?

Answer 18

Almost all nucleated cells

Question 19

What cells is MHC II found on?

Answer 19

APCs, B cells

Question 20

highly polymorphic genes

Answer 20

Genes of class Ia and class II

Question 21

what are some genes that are not highly polymorphic?

Answer 21

Class Ib and class III

Question 22

what are the most polymorphic HLAs?

Answer 22

class I HLA-B
class II HLA-DR

Question 23

Direct alloreactivity

Answer 23

Involves both CD8 and CD4 T cells
Donors APCs present to recipients Lymphocytes
self MHC recognizes the structure of an intact allogeneic MHC molecule

Question 24

Indirect alloreactivity

Answer 24

donor MHC is processed and presented by recipient APC
so donor MHC is handled like any other foreign antigen
Involves only CD4 T cells
Antigen presentation by MHC II

Question 25

Mixed Leukocyte Reaction

Answer 25

the higher the response
the higher the mismatch
to detect tissue incompatibilities by mixing leukocytes from potential donor with irradiated leukocytes from the potential recipient and vice versa
if mismatch donor leukocytes will proliferate and lyse host cells and vice versa

Question 26

Hyperacute rejection

Answer 26

occurs hours to days after transplantation - once the anastomosis is complete
target is vascular endothelium -> immediate thrombosis
destruction within 24-48 hrs
Graft destruction by antibody mediated and complement dep -> coagulative necrosis

Question 27

Acute rejection

Answer 27

most common seen
takes days to months after transplant (usually 3 months) - can 5 days or 6 months
classical, cell mediated rejection ( T cell mediated) - mostly CD4/8 T cells directed against donor MHC antigens
Target of current immunosuppression

Question 28

Chronic rejection

Answer 28

small percent of patients
slow, indolent process months to years after transplantation
has immune and non immune components - poorly defined
causes Ischemic injury - characterized by arteriole thickening and interstitial fibrosis
untreatable

Question 29

Hypersensitivity of Acute rejection

Answer 29

Type 2 and 4

see inflammation and swelling

Question 30

Hypersensitivity of chronic rejection

Answer 30

Type 2 but maybe type 3 or 4

Question 31

Graft vs. Host disease

Answer 31

seen with Bone marrow transplant
an immuno competent graft is transplanted into an immunology suppressed recipient
grafted cells survive and react against the host cells
GVH reaction is characterized by fever, pancytopenia, wt loss, rash, diarrhea, hepatosplenomegaly

Question 32

What are some methods of prevention and treatment of allograft rejection?

Answer 32

Immunosuppression
Reduce immunogenicity of allografts
Induce donor specific tolerance

Question 33

Immunosuppression is achieved by

Answer 33

drugs that inhibit or kill T lymphocytes
toxins that kill proliferating T cells
antibodies that deplete or inhibit T cells
anti inflammatory agents

Question 34

Reduce immunogenicity of allografts by

Answer 34

ABO blood typing

HLA typing and matching

Question 36

Induce donor specific tolerance through

Answer 36

Blood transfusions