Transplantation & Graft rejection

Question 1

What challenges are involved in transplantation?

Answer 1

~ availability of organs
~ surgical technique
~ graft rejection

Question 2

Autograft

Answer 2

tissue transplanted from one site of the body to another

e.g. skin after burns

Question 3

Isograft

Answer 3

graft of tissue from one genetically identical individual to another
e.g. monozygotic twins

Question 4

Allograft

Answer 4

graft of tissue from a donor to a recipient, needs good genetic match and immunosuppression

Question 5

Xenograft

Answer 5

~ transplantation of organs from animals to humans
~ currently not possible but under investigation
~ done the reverse in research

Question 6

Name the major antigens that need to match for a successful transplant.

Answer 6

~ ABO blood type

~ MHC molecules (HLA) - very polymorphic so often very between individuals

Question 7

What are the two types of ‘foreign’ graft recognition.

Answer 7

~ direct allorecognition

~ indirect allorecognition

Question 8

Direct allorecognition

Answer 8

donor-derived MHC-peptide complexes, typically presented by donor-derived ‘passenger’ dendritic cells, are recognised directly by recipient T cells

Question 9

Indirect allorecognition

Answer 9

Recipient T cells recognise the allopeptides bound to self-MHC molecules on recipient APCs

Question 10

Name the steps in graft rejection.

Answer 10

Days 3-7 = revascularization
Days 7-10 = cellular infiltration
Days 10-14 = thrombosis and necrosis

Question 11

Name the steps in graft acceptance.

Answer 11

Days 3-7 = revascularization
Days 7-10 = healing
Days 10-14 = resolution

Question 12

Treatment for transplantation

Answer 12

immunosuppressants which cause general immunosuppression = patients more susceptible to infections and some cancers