Intro To MHC & Transplantation Immunology

Question 1

MHC function

Answer 1

Help immune system differentiate between self and foreign particles

Question 2

MHC 1 vs MHC 2

Answer 2

• 1: CD8
• 2: CD4

Question 3

Leukocyte antigen types

Answer 3

• HLA: human
• BoLA: bovine
• SLA: swine

Question 4

Heterozygous animals

Answer 4

• 2 MHC alleles @ each locus
• express 6 diff. antigen presenting molecules

Question 5

Homozygous animals

Answer 5

• one MHC
• one allele coded for at each locus

Question 6

Iso/syngrafts

Answer 6

Transplant between clones/twins

Question 7

Reproductive allografts

Answer 7

Sperm, pregnancy

Question 8

Primary immune cells that distinguish self from foreign

Answer 8

T cells

Question 9

Steeper survival curve means

Answer 9

Lower survival & rejection

Question 10

Whats involved in graft rejection

Answer 10

• T cells
• blood vessels (1st attacked)
• antigen presenting cells
• MHCs

Question 11

Host/recipient graft rejection

Answer 11

• grafted APCs-> lymph nodes
• APCs (MHCII) encounter T cells reactive against graft
• APCs attacked

Question 12

Grafted tissue rejection events

Answer 12

• recipient blood flows thru graft
• entering t cells encounter MHC I & II & peptides
• APCs encounter grafted cells, etc
• if blood group is different, antigen antibody rxn occurs

Question 13

Hyperacute rejection

Answer 13

• minutes -> 48 hrs
• preexisting antibodies react
• immediate thrombosis & vascular destruction

Question 14

accelerated rejection

Answer 14

• within a wk
• cell mediated recognition of foreign MHC on graft cells

Question 15

Acute rejection

Answer 15

• weeks
• cell mediated (lymphocyosis)

Question 16

Chronic rejection

Answer 16

• months
• antibodies and cells (fibrosis)

Question 17

Prevention of allograft rejection

Answer 17

• match for compatibility
• dogs & cats reject renal allografts in 6-30 days if not given drugs
• azathioprine, cyclosporine, prednisolone, etc.

Question 18

Azathioprine

Answer 18

• interferes w/ DNA/RNA synthesis

Question 19

Cyclosporine

Answer 19

• interfere w/ lymphocyte signaling and cytokine response

Question 20

Prednisolone

Answer 20

• wide range
• not very potent
• given w/ other drugs

Question 21

Xenograft research usually conducted on

Answer 21

Immunodeficient mice that lack t and/or b cells

Question 22

Issues w/ pig to human xenografts

Answer 22

• pre-existing pig antibodies
• both species have different complement regulation
• delayed attack by generated antibodies
• disease transmission

Question 23

Pig & bovine heart valves

Answer 23

• transplanted since 60s
• Rx w/ gluteraldehyde to preserve and reduce immunogenicity

Question 24

Graft vs host disease (GVHD)

Answer 24

• Recipient doesn’t have immune rxn to destroy grafted immune-potent cells
• grafted cells destroy host
• bone marrow replacement therapy is a cause

Question 25

Why is sperm not rejected/ considered foreign

Answer 25

- seminal plasma is immunosuppressive & makes sperm non-immunogenic - prostatic fluid inhibits complement activation

Question 26

Why isnt fetus rejected

Answer 26

- lack of polymorphic MHC expression on trophoblast - non-polymorphic MHCs silence NK cells - Treg cells abundant in placenta - immunosuppressant molecules prevent lymphocyte activation - maternal antibodies against fetal MHCs can coat/protect placenta -close balance maintained until end of gestation-> rejection rxns

Question 27

Rejection rxns

Answer 27

Invasion of uterus by large # of immune cells

Question 28

Immune privileged sites & transplantation

Answer 28

Organs or tissues where survival of foreign grafts can be prolonged or immune responses suppressed/inhibited/subverted

Question 29

Cross matching

Answer 29

Checks if pre-existing antibodies in donor product or recipient serum/plasma are present

Question 30

Dogs and horses ____ have naturally pre-existing antibodies, so first time transfusions can be run _______ cross match

Answer 30

Don’t; without (Needs a cross match for 2nd transfusion)

Question 31

Major crossmatch testing

Answer 31

Check RBC from donor against serum from recipient

Question 32

Minor crossmatch testing

Answer 32

Check serum from donor against RBC from recipient