Week 2 Flashcards

1
Q

A molecular structure, associated with a cell membrane, that may illicit an immune response.
• Found on viruses, bacteria, fungi, protozoa, blood cells, organs and tissues.

A

Antigen

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2
Q

Glycoprotein that recognises a particular

epitope on an antigen and facilitates clearance of that antigen.

A

Antibody (Immunoglobulin):

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3
Q

What genes at three separate loci control the occurrence and location of ABO antigens on
cells and in secretions?

A

H gene, ABO genes, Se (Secretor) gene

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4
Q

A gene that has no detectable product or phenotypic effect is called a _________

A

Amorph

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5
Q

List the alleles for each of the following genes

H gene, ABO genes, Se (Secretor) gene

A
  • H and h alleles (h is an amorph)
  • A, B and O alleles (O is an amorph)
  • Se and se alleles (se is an amorph)
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6
Q

H antigens are an indirect product are the foundation for which antigens?

A

Foundation for A and B antigens

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7
Q

A common structure for A,B and H antigens is an ________________ chain

A

oligosaccharide

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8
Q

H allele codes for a transferase enzyme that adds a sugar (fucose) to the terminal sugar of the oligosaccharide chain which makes a ____________

A

H antigen

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9
Q

“A” gene codes for a transferase enzyme

that adds ______________ to the terminal sugar of H antigen.

A

N-acetylgalactosamine

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10
Q

“B” gene codes for a transferase enzyme that adds__________ to the terminal sugar of the H antigen

A

D-galactose

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11
Q

Which alleles are co-dominant and which is silent

A

A and B alleles are co-dominant , O allele is silent

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12
Q

Soluble antigens (A, B, and H) can be found in the secretions of some individuals. • This is controlled by the ________ genes

A

H and Se

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13
Q

Which genotypes are secretors and which genotypes are non secretors?

A

SeSe and Sese are secretors - 80% of the population.

sese are non secretors. se is an amorph nothing is expressed.

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14
Q

ABO subgroups differ in amount of …..

A

antigen present on the RBC membrane

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15
Q

What are the two major subgroups of A

A

A1 and A2
• A1 - ~80% of group A or AB individuals
• A2 - ~20% are A2 or A2B

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16
Q

What’s the difference between A1 and A2 Antigens? (2)

A

Quantitative difference

Difference in carbohydrate composition

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17
Q

Can A2 develop anti-A1 antibodies?

A

Yes

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18
Q

Why is the A2 phenotype important?

A

A2 and A2B individuals may produce an anti-A1 causing an incompatibility crossmatch

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19
Q

What is the Bombay phenotype?

A

(Oh) it’s an Inheritance of hh the h gene is an amorph With no H Ag’s, cannot make A or B Antigens

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20
Q

Does the Bombay serum have strong anti-A, anti-B and anti-H?

A

Yes

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21
Q

The Bombay RBC’s appear to be what blood type? and what agglutinates with the serum?

A

Appears to be O and it agglutinates ALL ABO blood groups even O.

22
Q

What ABO groups could you transfuse Bombay phenotype blood to?

A

Can transfuse Bombay phenotype to anyone

23
Q

What ABO blood group could you transfuse to patient with Bombay group?

A

Individuals with Bombay phenotype can only receive blood from a Bombay phenotype.

24
Q

Only blood group system where antibodies are present in individuals with no known exposure to blood or blood products

A

ABO blood group system

25
Q

Transfusion of incompatible group may result in __________

A

immediate lysis of donor RBC

26
Q

Can newborns passively acquire maternal antibodies?

A

Yes. IgG can cross the placenta

27
Q

The Anti-B produced by group A individuals and the Anti-A produced by group B individuals is predominantly _______

A

IgM

28
Q

The Anti-A, Anti-B and Anti-A,B produced by group O individuals is predominantly________

A

IgG (with some IgM)

29
Q

Which blood groups contain anti-A in their serum

A

Group O and B

30
Q

Anti-A can be separated into what 2 different components?

A

Anti-A and Anti-A1

31
Q
Anti - A1
Clinically Significant?
Abs Class?
Thermal range?
HDNB?
Extravascular or Intravascular Transfusion reaction?
A

Clinically Significant? - Sometimes
Abs Class? IgM
Thermal range? 4 - 22
HDNB? No because IgM cannot pass the placenta
Extravascular or Intravascular Transfusion reaction? - Rarely intravascular

32
Q

Anti-AB is found in serum of which blood group?

A

Group O individuals

33
Q
Anti-A, Anti-B, Anti-AB
Clinically Significant? 
Abs class 
Thermal range 
HDNB 
Transfusion reaction?
A
Clinically Significant? - Yes
Abs class - IgM, IgG
Thermal range - 4-37
HDNB - Yes
Transfusion reaction? Yes both Extravascular and Intravascular
34
Q

Rh is the most complex system with over 50 Rh antigens described. What are the 5 principal antigens?

A

– D, C, c, E, e

35
Q

Rh antigens are _________

A

proteins

36
Q

What is the current inheritance theory:

A

2 loci on the short arm of Chromosome 1

37
Q

What are the 2 naming systems developed before advances in molecular genetics

A
  • Fisher-Race

* Wiener

38
Q

What are the additional systems developed so universal language available for use with computers

A
  • Rosenfield

* ISBT

39
Q

Fisher-Race terminology looks like ______

Wiener terminology looks like ________

A

Fisher - CDE, cde

Wiener - r’, R1

40
Q

When there is no Rh antigens present on the RBC membrane what can be seen on a blood film and why?

A

Stomatocytosis because Rh antigens are integral part of RBC membrane, absence leads to loss of membrane
integrity. mild hemolytic anaemia

41
Q

What test do Rh antibodies agglutinate in?

A

IAT

42
Q
Rh antibodies:
Clinically Significant? 
Abs class 
Thermal range 
HDNB 
Transfusion reaction?
A
Clinically Significant? Yes 
Abs class  - IgG
Thermal range  - 4-37
HDNB - Yes
Transfusion reaction? Only Extravascular not Intravascular
43
Q

After ABO, the Rh system is the second most important system, why?

A

D antigen is extremely immunogenic. If D neg patients are exposed to D antigen they will most likely make Anti-D antibody.

44
Q

Will individuals produce antibodies to ABO antigens they do not possess or that they do possess?

A

Do not posses

45
Q

For a Forward group – tile or slide what do you need to add?

A

Anti-serum: Anti-A, Anti-B, Anti-D + the patients red cells

46
Q

For the Reverse Group what do you add?

A

Patient plasma + commercial red cells A1, B

47
Q

Most ABO discrepancies are ______ in nature and can be resolved by doing what 3 things?

A

Technical

  1. Correctly repeating the test
  2. Carefully checking reagents
  3. Careful reading and recording of results
48
Q

Give 2 examples of ABO discrepancies that are antibody related.

A
  • New born infants, elderly patients
  • Patients with lymphoma.
  • Patients using immunosuppressive drugs e.g BM transplant
  • Patients with immunodeficiency disease
49
Q

Give 2 examples of ABO discrepancies - Antigen related

A

Can be seen in patients with leukaemia and Hodgkin’s disease and some bacterial infections

50
Q

What are some ABO discrepancies - Serum related

A

Elevated levels of globulin lead to rouleaux formation
• Multiple myeloma
• Hodgkin’s lymphoma
(to resolve wash patients red cells in saline)

51
Q

List some steps as a scientist that you would do to resolve a ABO discrepancies

A
  • check patient diagnosis and transfusion history
  • check for technical errors
  • have a second scientist repeat the test
  • incubate patients serum for 15min at room temp
52
Q

When D antigen is weakly expressed, detection requires what test?

A
indirect antiglobulin testing (IAT)
• Incubate cells with Anti-D antisera
• Wash
• Perform antiglobulin test to detect presence of Ig bound to cells
• Cannot be done if cells at DAT +ve