Organ-Graft Rejection, Neonatal immunity

Question 1

Describe the differences between an allo-, auto-, xeno-, and iso- graft/antigen

Answer 1

Auto = component of hosts own body and recognized by immune system

Allo = from a genetically unrelated member of the same species

Xeno = from a different species

Iso= twins (carry the same antigens)

Question 2

What two histocompatibility antigens can trigger an immune response in a transplant?

Answer 2

Blood antigens

MHC I or II

Question 3

A transplant will last the longest if what are compatible?

Answer 3

Blood antigens, and both MCHI and MHCII

Question 4

What are the innate immune reactions leading to graft rejection?

Answer 4

Graft damage -> release of cytokines, inflammatory mediators, and DAMPS -> activate neutrophils and macrophages -> increase inflammation

NK - apoptosis
Complement -C3a and C5a increase the presence of phagocytic cells

Question 5

What adaptive mechanisms lead to graft rejection

Answer 5

Antigens from the graft are recognized by host APC or donor/graft APC –> present to host Tcells -> humoral and cellular response

Question 6

What occurs in the graft tissue leading to rejection?

Answer 6

Destruction of endothelial cells
Hemorrhage
Platelet aggregation and thrombosis 
Cytotoxic cytokines 
Macrophage phagocytosis

Question 7

________________ drugs allow for longer survival of a tissue/organ transplant

Answer 7

Immunosuppressive

Eg 
Azathioprine 
Prednisone 
Cyclosporine 
Lefunomide

Question 8

What about privileged organs or tissues allows most transplants to be successful ?

Answer 8

Decreased contact with immune cells

• > blood-tissue barrier
• > lack DC
• > low level of MHC I or II
• > immunosuppressive molecules
• > block NK cell lysis
• > suppress NO production
• > express CD95L (Tcell apoptosis)

Question 9

What are the privileged tissues?

Answer 9

Anterior chamber of the eye
Cornea
Thymus
Testes
Brain

Question 10

What disease occurs when the graft mounts an immune response against the host?

Answer 10

Graft vs host disease

Eg bone marrow transplants

Question 11

A graft from animals to humans is called a ____________. What can be a concern in this type of graft?

Answer 11

Xenograft

Spread of zoonotic disease

Question 12

If a fetus comes in contact with a pathogen, ________ can be induced

Answer 12

Tolerance

Question 13

When is the fetus most susceptible to infection?

Answer 13

Before development of the thymus

Question 14

What is the fate of a fetus that has a developed immune system that encounters an infection in utero

Answer 14

Can develop normally-> developed immune system eliminates virus

Question 15

Newborns ingesting colostrum are getting ________ ___________ adaptive immunity

Answer 15

Passive natural

Question 16

What is the major antibody type in colostrum

Answer 16

IgG

Question 17

What is the major antibody class in ruminant milk?

Answer 17

IgG

Question 18

What is the major antibody class in nonruminant milk?

Answer 18

IgA followed by IgG

Question 19

What is the purpose of colostrum in the newborn immunity compared to milk?

Answer 19

Colostrum protects against septicemic disease

Milk offers protection against only enteric infection

Question 20

What conditions can lead to failure of natural passive immunity transfer from he mother to the newborn?

Answer 20

Premature birth-> mother not formed colostrum yet
Premature lactation-> loss of colostrum prior to birth
Failure of neonate to suckle in first 24hrs
Failure of neonate to absorb colostrum

Question 21

Why do you wait to give newborns vaccinations?

Answer 21

If maternal antibodies are present-> bind to injected antigens and pathogens –> accelerate their clearance

Or maternal antibodies bind to critical epitope which prevents Bcell activation and Ab production by the newborn

Question 22

The (higher/lower) the titer of the mother, the older the offspring need to be for effective vaccination

Answer 22

Higher

Question 23

How does passive natural immunity work in the chick?

Answer 23

In the ovary, IgY is deposited into yolk from blood (absorbed into chicks bloodstream)

Oviduct secretes IgA into albumin (will be ingested by chick)