Fetal Transplant

Question 1

What is the main barrier to transplant?

Answer 1

MHC compatibility

Question 2

What is an autograft?

Answer 2

Self to self

Question 3

What is an isograft?

Answer 3

Self to identical twin

Question 4

What is an allograft?

Answer 4

Person to person

Question 5

What is a xenograft?

Answer 5

Interspecies

Question 6

How do lymphocytotoxic Ab function?

Answer 6

Incubate recipient serum with lymphocytes of known HLA.

If there are HLA antibodies in the serum they will bind to their MHC antigen on the lymphocyte cell surface.

Complement is then added to all the wells. Lymphocytes that have bound antibody on their MHC will be lysed.

Since the MHC is known for each lymphocyte well, the exact anti-MHC specificity can be determined.

Question 7

What is the mixed lymphocyte reaction?

Answer 7

Mixing MHC T cells from the recipient with the MHC non-T cells of the donor as APCs (that have been paralyzed) and measure the T cell proliferation and detection of CD8 cells to determine the immune response.

Question 8

What is direct Ag presentation?

Answer 8

Activation of the immune system occurs through the foreign MHC occurs without MHC processing or Ag presentation via the “passenger leukocytes”

Question 9

Why is direct Ag presentation a HERESY?

Answer 9

There is not MHC Ag presentation

Question 10

What is indirect Ag presentation?

Answer 10

It is the classic presentation method with the allo-Ag uptaken and presented on Class II MHC by APCs to CD4 cells

Question 11

What is hyper acute rejection and why does it occur?

Answer 11

It is accelerated rejection that will occur due to the presence of the allo-Ab complex within 48 hours. This occurs due to the prior presence of Ab as in pregnancy sensitization or difference in blood types.

Question 12

What is acute rejection?

Answer 12

Anti-donor cells that are formed within 3 weeks due to TMMI reaction via CD4 with B cell Th2 and Th17 response following after

Question 13

What is chronic rejection?

Answer 13

Slow graft attrition with arteriolar narrowing which causes intimate thickening and graft ischemia

Question 14

What are the difficulties of bone marrow transplant?

Answer 14

Causes a graft VS host disease that occurs with the marrow forming Ab against the host as the host is in an immunocompromised state

Question 15

What is the main gene that is a problem fro xenotransplantation?

Answer 15

Inactivation of alpha-1,3-Gal gene that is absent in higher primates

Question 16

What MHC is displayed at the fetal-maternal interface instead of the normal MHCs?

Answer 16

HLA-G is displayed instead of A/B/C.

Question 17

What is the function of HLA-G?

Answer 17

It functions to inhibit maternal NK cells

Question 18

What happens to cytokine genes that promote CD8?

Answer 18

Downregulated

Question 19

What is unique about the NK cells in the uterus in pregnancy?

Answer 19

They lack CD16 and do not have ADCC

Question 20

What is the status of gamma-delta T cells?

Answer 20

They are present in high amounts

Question 21

What is the systemic immune balance shifted towards in pregnancy?

Answer 21

Progesterone presence will inhibit the Th1 responses and instead increase the Th2 response

Question 22

What Tregs are increased in pregnancy?

Answer 22

Paternal MHC Ag Tregs are increased in pregnancy

Question 23

What is the function of DAF display and what triggers it?

Answer 23

DAF display is triggered by progesterone

It functions to inhibit complement mediation

Question 24

What is the problem with the Th2 preference of pregnancy?

Answer 24

It exacerbates diseases that need Th1 responses like flu and tuberculosis

Question 25

What happens if Th1 is dominant in pregnancy?

Answer 25

Fetal loss

Question 26

What can happen with the infection of the fetus in pregnancy?

Answer 26

It may lead to tolerance of the pathogen in the future

Question 27

What happens when maternal T lymphocytes contact the fetus?

Answer 27

When maternal T lymphocytes (ly) come in contact with fetal ly (maternal & paternal MHC) at the placental interface maternal ly or in the fetus itself, they are converted by fetal TGF- to paternal specific T-regs.