Transplantation

Question 1

What is a graft?

Answer 1

A piece of tissue that is transplanted

Grafts can be used in various medical procedures, including organ transplants.

Question 2

What is a transplant?

Answer 2

A procedure in which an organ/s, tissue or group of cells are removed from one person (the donor) and transplanted into another person (the recipient), or moved from one site to another in the same person.

Question 3

What is an autograft?

Answer 3

Tissue grafted back onto the original donor.

Question 4

What is an isograft?

Answer 4

A graft between syngeneic individuals (i.e., of identical genetic constitution) such as identical twins.

Question 5

What is an allograft?

Answer 5

A graft between allogeneic individuals (i.e., members of the same species but different genetic constitution), for example, human to human.

Question 6

What is a xenograft?

Answer 6

A graft between xenogeneic individuals (i.e., of different species), for example, pig to human.

Question 7

What are the risks associated with allografts?

Answer 7

Risk of graft versus host disease (GVHD) and rejection.

Question 8

What is the most common allograft?

Answer 8

Blood transfusion.

Question 9

What can result from blood transfusion mismatching?

Answer 9

Haemolysis, intravascular coagulation, chills, and nausea.

Question 10

What are major antigens that can trigger graft rejection?

Answer 10

Major Histocompatibility Antigens (MHC), also known as HLA in humans.

Question 11

What are minor histocompatibility antigens?

Answer 11

Antigens such as HY and HA1 that can also trigger graft rejection.

Question 12

What are the classes of HLA alleles?

Answer 12

Class I (HLA-A, HLA-B, HLA-C) and Class II (HLA-DP, HLA-DQ, HLA-DR).

Question 13

What is the inheritance pattern of HLA?

Answer 13

Each child inherits one HLA haplotype from each parent, leading to various possible combinations.

Question 14

What is the probability of a random pair having identical HLA specificities?

Answer 14

Very low.

Question 15

What percentage of T-cells in normal individuals react with alloantigens?

Answer 15

Upwards of 10%.

Question 16

What are the two pathways of donor antigen presentation?

Answer 16

Direct and indirect pathways.

Question 17

What characterizes hyperacute rejection?

Answer 17

Rejection occurs within minutes.

Question 18

What characterizes acute rejection?

Answer 18

Rejection occurs within several days.

Question 19

What characterizes chronic rejection?

Answer 19

Rejection occurs within months to years.

Question 20

What is the pathogenesis of hyperacute rejection?

Answer 20

Circulating antibodies specific for antigens on the graft endothelial cells activate complement and clotting cascades.

Question 21

What is the pathogenesis of acute rejection?

Answer 21

Graft infiltration with cytotoxic T cells and cytokine-mediated recruitment of other cells.

Question 22

What are the risk factors for acute rejection?

Answer 22

Degree of HLA (mis)matching.

Question 23

What is the pathogenesis of chronic rejection?

Answer 23

Not fully understood; can involve lymphocytes, phagocytes, antibody, and complement.

Question 24

What is HLA matching?

Answer 24

A method to maximize immunological acceptance of the graft by matching donor and recipient antigens.

Question 25

What techniques are used to identify HLA alleles?

Answer 25

* Serology * Sequencing or typing * Cross-matching

Question 26

What is cross-matching?

Answer 26

A technique used to investigate whether the recipient has previously reacted to the HLA molecules that will be presented on the donor organ after transplantation.

Question 27

What is the risk of over-suppression of the immune system?

Answer 27

Increased susceptibility to infections, drug side effects, and other diseases.

Question 28

What are common side effects of ciclosporin?

Answer 28

* Tremor * Hypertension * Gum hypertrophy * Hirsutism

Question 29

What are the sources of haematopoietic stem cells?

Answer 29

* Bone marrow * Peripheral blood * Umbilical cord

Question 30

What is graft versus host disease (GVHD)?

Answer 30

A condition where donor immune cells attack the recipient's tissues.

Question 31

What are common treatments for GVHD?

Answer 31

* High dose steroids * Immunosuppressants * Faecal microbial transplant * Ruxolitinib

Question 32

What is CMV disease?

Answer 32

Cytomegalovirus disease that most commonly affects the lung, GI tract, eye, liver, or CNS.

Question 33

What is the most serious complication of CMV pneumonia?

Answer 33

50% mortality rate.

Question 34

What is PTLD?

Answer 34

Post transplant lymphoproliferative disease driven by immunosuppression, often associated with EBV.