14 - Transplantation Immunology

Question 1

What determines the recognition as self or foreign of certain transplant?

Answer 1

Genes of the MHC ▶️ expressed in a codominant fashion

Inherited as set or haplotypes ▶️ difference between genetically unrelated individuals

Question 2

Why could a syngenic graft be rejected? Which is the only graft that is not rejected?

Answer 2

Somatic mutation

Autografts

Question 3

Type of graft rejection that can cause an ABO incompatibility.

Answer 3

Hyperacute

Question 4

How can you look for preformed antibodies reactive against allogenic HLA molecules? What patients may have these antibodies?

Answer 4

Cross-matching ▶️ mix serum from host with potential donor lymphocytes
Previous pregnancies, transfusions, transplantations ▶️ hyperacute graft rejection

Question 5

What cells mediate rejection of bone marrow transplants (host vs graft) by the recipient?

Answer 5

Lymphokine-activated killer (LAK) cells and NK cells

Question 6

Allogenic transplantation in which immunosuppression is not required. Why is it a immunoprivileged site? What other organs are immunoprivileged?

Answer 6

Corneal transplantation
Lack of lymphatic vessels ▶️ alloantigens of the graft cannot sensitize the host lymphocytes
Uterus, testes, brain, thymus

Question 7

What is the root of almost all graft rejection?

Answer 7

T-cell sensitization

Question 8

Which type of cytokine can increase the expression of MHC class I and II as well? Clinical use

Answer 8

IFNs of all types

Make some tumor cell lacking of MHC I more susceptible to be recognized and killed by CD8