Transplantation of Tissues and Organs Flashcards

1
Q

Define “histocompatible”

A

Donor and recipient have compatible tissue types that can coexist without provoking too strong of an immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

True or false. Autologous transplantation can trigger hypersensitivity reactions.

A

False. Autologous are your own cells. Allogenic transplantation (i.e. from another person) can trigger hypersensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why do we produce antibodies against A and/or B antigens?

A

Cross-reactive with cell-surface carbohydrates of common commensal bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does cross-match testing before transfusions work?

A

Agglutination of donor red blood cells if the antibody is present in serum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

True or false. After multiple transfusions, it may be difficult to find a compatible donor.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Blood group incompatibility can cause type ____ hypersensitivity, leading to fevers, chills, shock, renal failure, or death

A

Type II (hemolytic reactions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where are ABO antigens present aside from erythrocytes?

A

Endothelial cells of blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Incompatible donor/recipient transplant causes antibodies to quickly and extensively bind the blood vessels of the graft. Complement is fixed throughout the graft’s vasculature resulting in _______

A

Hyperacute rejection (can happen on the table)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does cross-match testing work in regard to HLA I and II?

A
  • Detects antibodies in patients serum that can trigger complement mediated lysis of donor lymphocytes
    • anti-HLA I antibodies react with B and T-cells
    • anti-HLA II react with B cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is flow cytometry more specific that cross-matching?

A

It detects ALL antibody binding, not just those that fix complement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Under what circumstances could the body potentially make anti-HLA antibodies?

A
  • Pregnancy → fetus expresses parental HLA; exposed after trauma of birth
  • Blood transfusions
  • Previous transplant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the main source of anti-HLA antibodies used in serological HLA typing?

A

Multiparous women (have given birth more than once)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference between transplant rejection and graft-versus host reaction (GVHR)?

A
  • Transplant rejection involves a solid organ transplant
  • GVHR involves hematopoietic stemm cell transplantation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

_____ occurs when donor T-cells respond to and attack the recipient’s healthy tissue (type IV hypersensitivity).

A

Graft-versus host disease (GVHD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

____ is when a patient’s tissue is transplanted from one site to another (ex: skin graft, bone graft, ligament repair)

A

Autograft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

_____ involves transplant between two genetically identical individuals

A
  • Isograft
  • Syngenic transplant
17
Q

_____ occurs when a transplant recipient’s naive T-cell population contains clones that recognize HLA allotypes of the transplanted tissue. Takes days to develop

A

Acute rejection

18
Q

In acute rejection, CD8 T-cells respond to HLA _____, while CD4 T-cells respond to HLA ____.

A
  • CD8 → HLA I
  • CD4 → HLA II
19
Q

Patients are conditioned with ____ before and after transplantation to hdiminish e risk of acute rejection.

A

Immunosuppressive drugs

20
Q

Explain the direct pathoway of allorecognition

A

Recipient T-cells are stimulated by direct interaction of their receptors with the allogenic HLA molecules expressed by donor dendritic cells

21
Q

______ rejection is a type III hypersensitivity caused by IgG against HLA I of graft tissue, forming immune complexes that deposit in blood vessels of transplanted organs. Can occur up to 10 years after transplant.

A

Chronic rejection

22
Q

In chronic rejection, grafts become infiltrated with _____ expressing B-cells and _____ expressing T-cells

A
  • CD40 expressing B-cells
  • CD40-ligand expressing T-cells
23
Q

What is the function of rituximab?

A
  • Anti-B-cell antibody
  • Treats chronic rejection
24
Q

Explain the indirect pathway of allogenic recognition.

A
  • Activation of helper CD4 T-cells by graft HLA after transplantation
  • Induces naive B-cells to become plasma cells
    • only occurs if naive B-cells are capable of reacting with graft HLA
25
\_\_\_\_\_\_ - regulatory CD4 T-cells suppress alloreactive CD4 and CD8 T-cells. More active in patients with previous blood transfusions with shared HLA-DR allotype of graft.
Transfusion effect
26
What animal is the most suitable donor species for xenotransplantation? Why?
Pigs * Organs are similar in size * Farmed, slaughtered, and consumed by humans in large numbers (less likely to trigger hypersensitivity)
27
What is the funciton of myeloablative therapy in hematopoietic stem cell transplantation?
* Cripples the recipient's immune system * Creates spece for donor cells in bone marrow niche
28
How long after hematopoietic stem cell transplantation does it take for RBCs to be produced? How long to completely reconstitute the immune system?
* 2-3 weeks RBCs * ~1 year for full reconstitution