solid organ transplantation Flashcards

1
Q

what is autologous transplant

A

donor and recipient are the same individual (most common)

- e.g. skin graft

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2
Q

what is syngeneic transplant

A

donor and recipient are genetically identical twins

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3
Q

what is allogenic transplant

A

donor and recipient are not genetically identical but are from same species

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4
Q

what is xenogenic transplant

A

donor and recipient are from different species.

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5
Q

what are the types of allogenic donors

A
Living donors:
haematopoietic stem cells- bone marrow transplant
Kidney- 1 kidney
liver lobe
lung lobe- parents donating to a child
Deceased donors:
Kidney- both kidneys
liver
pancreas
heart (and lung) 
cornea
 and other tissues
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6
Q

What are the compatible donors for blood type A

A

A,O

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7
Q

What is the antigen on RBC and antibody in plasma for people with blood type A

A

Antigen on RBC- A

Antibodies against- B

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8
Q

What are the compatible donors for blood type B

A

B,O

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9
Q

What is the antigen on RBC and antibody in plasma for people with blood type B

A

Antigen on RBC- B

Antibodies against- A

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10
Q

what are the compatible donors for blood type AB

A

O,A,B,AB

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11
Q

What is the antigen on RBC and antibody in plasma for people with blood type AB

A

Antigen on RBC- A,B

Antibodies against- No antibodies against it

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12
Q

what are the compatible donors for blood type O

A

O

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13
Q

What is the antigen on RBC and antibody in plasma for people with blood type O

A

No antigen on RBC

Antibodies against- A, B

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14
Q

what is Hyperacute rejection of transplanted organ

A

occurs immediately after connection of blood vessels.

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15
Q

how can the problem of Hyperacute rejection be overcome

A

immunoadsorption, plasma exchange, immunosuppression (limited to living donors)
taking away antibodies of the recipients- only appropriate when donor is a living donor so can be planned in advance

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16
Q

what chromosomes are the Major histocompatibility complex (MHC) located on and what genes do they contain

A

Located on chromosome 6 and contains our HLA genes

17
Q

what is the structure of HLA class 1 and what exons is the polymorphism located on

A

3 alpha
1 beta chains

Polymorphism located on exons 2 and 3

18
Q

what is the structure of HLA class 2 and what exons is the polymorphism located on

A

2 alpha
2 beta chains

Polymorphism located on exon 2

19
Q

describe the expression of HLA class 1 (types and what it is present on)

A

HLA class 1:
A
B
C

Present on all nucleated cells

20
Q

describe the expression of HLA class 2 (types and what it is present on)

A

HLA class 2:
DQ
DR
DP

present on APCs (macrophages, dendritic cells and B cells)
Present on activated T cells

21
Q

what is alloreactivity and how is it overcome

A

T-cells respond vigorously to non-self HLA molecules .

Major obstacle for transplantation - aim is to match HLA molecules

22
Q

Describe HLA matching in kidneys, liver and cardiothoracic

A

Kidneys: aim to match HLA-A, B, DR
Liver: HLA matching not performed
Cardiothoracic: Not feasible due to logistics

23
Q

Patients can make antibodies against non-self HLA via what routes?

A

Pregnancy- mother sensitised to HLA type of baby that has been inherited from father- so makes harmless antibodies against them

Blood transfusion- sensitised to HLA type of blood donor

Previous transplant

24
Q

Describe hyperacute transplant rejection

A

Patient has pre-formed complement fixing donor reactive antibodies.
Occurs mins/hours after transplant
Extremely rare

25
Describe acute rejection
Immune mediated: T-cells (cellular) and B-cells (antibodies) Treat with modulation of immunosuppression Risk factor for chronic allograft nephropathy
26
Describe chronic allograft nephropathy
Progressive damage to organs | More slowly compromises organ function than acute rejection
27
what do HLA class I molecules bind
Binds proteins derived from intracellular proteins, including peptides derived from virus
28
what do HLA class II molecules bind
Binds peptides dervied from extracellular proteins and cell surface proteins, including peptides derived from bacteria
29
what are the two tiers of transplant allocation and describe them
Tier A- Patients with match-ability score = 10 Patients with 100% calculated reaction frequency Patients that have accured 7 years of waiting time Tier B: all other eligible patients (kidney only)
30
what does matchability score mean
Matchability score=1 means easy to find HLA matched donor | Matchability score=10 means hard to find HLA matched donor
31
what does 100% calculated reaction frequency mean
Prescence of HLA antibodies in patient: 0% = none 100% = antibodies present that react with multiple HLA mismatches