HLA and Tissue Typing Flashcards

1
Q

What does HLA stand for?

A

Human Leucocyte Antigens

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2
Q

What is the role of HLA?

A

Determines if something ‘belongs’ to the body or not.

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3
Q

How many classical loci of HLA are there?

A
  1. Class I (A,B,C) and Class II (DR, DQ, DP)
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4
Q

What are the Class I HLA loci?

A

A, B ,C

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5
Q

What are the Class II HLA loci?

A

DR, DQ, DP

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6
Q

What is the purpose of loci molecules in HLA?

A

Allow tissue to be recognised as ‘self’ or ‘non self’ by host immune system to determine histocompatibility.

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7
Q

What chromosome is HLA found on?

A

Chromosome 6

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8
Q

Where is the HLA region located on chromosome 6?

A

On the short arm

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9
Q

Which HLA class are expressed on almost ALL cells?

A

HLA Class I

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10
Q

Which HLA class recognise intracellular pathogens?

A

HLA Class I

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11
Q

Which HLA class are found on immune cells?

A

HLA Class II

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12
Q

Which HLA Class recognise extracellular pathogens?

A

HLA Class II

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13
Q

How are HLA very Polymorphic?

A

They have many different alleles. Serve to recognise and initiate an immune response.

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14
Q

Which HLA Class are expressed on all nucleated cells?

A

HLA Class I

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15
Q

Which HLA Class are expressed on antigen-presenting cells?

A

HLA Class II

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16
Q

What does HLA-A define on nomenclature?

A

The locus

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17
Q

What does HLA-A24 show on nomenclature?

A

The antigen has been serologically defined

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18
Q

What does the asterisk in ‘HLA-A*24’ show?

A

This shows that the allele was defined through low resolution molecular methods.

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19
Q

What does the ‘:’ in HLA-*24:01 show?

A

This shows a specific allele from a higher resolution.

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20
Q

How many antigens and alleles does HLA A have?

A

28 antigens. 1729 alleles.

21
Q

How many antigens and alleles does HLA B have?

A

60 antigens. 2329 alleles.

22
Q

How many antigens and alleles does HLA C have?

A

10 antigens. 1291 alleles.

23
Q

How many antigens and alleles does HLA DR have?

A

21 antigens. 1051 alleles.

24
Q

How many antigens and alleles does HLA DQ have?

A

9 antigens. 160 alleles.

25
Q

How many antigens and alleles does HLA DP have?

A

6 antigens. 150 alleles.

26
Q

What percentage of England have HLA type A*24?

A

10.5%

27
Q

What is the percentage of HLA A*24 in Columbia?

A

26.2%

28
Q

What is significant about HLA B46?

A

This is 0% in most countries but 29% in Thailand. (10% in Japan)

29
Q

Who MUST have their HLA loci determined?

A

All potential organ recipients and donors so that rejection is minimised.

30
Q

What are Terasaki trays?

A

Plates used in HLA serology that contain serum with anti-HLA antibodies. A patients cells and complement are added and if the antibody reacts with patients sample then death occurs.

31
Q

What does the green dye show in a terasaki tray?

A

Live cells

32
Q

What does red dye show in terasaki trays?

A

Dead cells.

33
Q

What do ALL molecular methods of HLA typing require?

A

Require the extraction of high quality genomic DNA.

34
Q

What is used by NHS labs to carry out molecular HLA typing?

A

A semi-automated system that extracts genomic DNA from whole blood.

35
Q

Where else can genomic DNA be isolated from for HLA molecular typing?

A

Buccal swabs, Saliva samples, Fingernails.

36
Q

What is an SSP in molecular HLA typing?

A

Sequence Specific Primer (SSP). Often the first step.

37
Q

What is often the first step in HLA molecular determination?

A

SSP.

38
Q

What does a Sequence Specific Primer consist of?

A

Multiple PCR primers that are specific to known HLA polymorphisms (antigens/alleles). These are supplied in a kit.

39
Q

What does a SSP produce?

A

Specific amplicons are produced from PCR if the primers are complimentary to sample patient DNA.

40
Q

How many people have HLA-B27?

A

8%

41
Q

What are risks associated with HLA-B27?

A

Risk of ankylosing spondylitis (spinal inflammation) and other inflammatory disorders.

42
Q

What percentage of Ankylosing Spondylitis sufferres are HLA-B27 positive?

A

95%

43
Q

What disorder is associated with HLA-B57?

A

Drug induced inflammatory disorder.

44
Q

What two HLA types are patients screened for prior to UK treatment?

A

HLA-B27. HLA-B57.

45
Q

What is a major risk factor associated with hyperacute rejection?

A

Recipients may have antibodies to antigens that are expressed on donor cells.

46
Q

Where might anti-HLA antibodies develop from?

A

Pregnancy. Blood transfusion. Previous transplantation.

47
Q

What is a CDC crossmatch? When is it done?

A

Carried out right before surgery. Recipient sera is incubated with donor lymphocytes in the presence oof complement.

48
Q

What does CDC stand for?

A

Complement Dependent Cytotoxicity