ABO & Carbohydrate Ags Flashcards

1
Q

ABO, Lewis, H, I and i are all what type of antigens?

A

Carbohydrate

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2
Q

Carbohydrate antigens are affected by genes that encode for what?

A

enzymes

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3
Q

Genes for protein antigens encode for what?

A

Structural proteins

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4
Q

Carbohydrate Vs. Protein Antigens:

-Naturally occuring

A

Carbohydrate

*Antibodies acquired only after exposure to products containing antigens

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5
Q

Carbohydrate Vs. Protein Antigens:

-Antibody type (IgG/IgM)

A

Carbohydrate - IgM

Protein - IgG

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6
Q

Carbohydrate Vs. Protein Antigens:

-Temperature

A

Carbohydrate - RT

Protein - 37 degrees

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7
Q

Carbohydrate Vs. Protein Antigens:

-“agglutinating” vs. “coating”

A

Carbohydrate - Agglutinating

Protein - Coating

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8
Q

Carbohydrate Vs. Protein Antigens:

  • React at AHG phase
  • React at IS phase
A

Protein - AHG phase

Carbohydrate - IS phase

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9
Q

How are H antigens made?

A

Type 1 and Type 2 precursor carbohydrates by the enzyme products of the:

  • H (FUT1) genes
  • Se (FUT2) genes
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10
Q

In secretions (saliva, tears) and in plasma, Type __ chains are converted into H antigen by _____ of the ____ gene product.

A
  • Type I
  • Fucosylation
  • Se (FUT2)
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11
Q

On the surfaces of RBC, Type __ chains are converted into H antigen by _____ of the ____ gene product.

A
  • Type 2
  • Fucosylation
  • H (FUT1)
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12
Q

Fucosyltransferase 1/2 (FUT1/2) adds _____ to type 1/2 chains at the terminal _______.

A
  • Fucose

- Galatacose

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13
Q

Se (“secretor”) gene (FUT2) frequency.

A

80%

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14
Q

H gene gene (FUT1) frequency.

A

virtually 100%

*Bombay = hh

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15
Q

T/F: H antigen is required before A and/or B can be made on RBCs or in Secretions.

A

True

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16
Q

Lewis antigens are made from type __ precursor by the enzyme product of _____ gene.

A
  • Type I (Secretor)

- Le (FUT3) gene

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17
Q

Secreted Le(b) and Le(c) are receptors for what?

A
  • Norwalk virus

- H. pylori

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18
Q

Le(a) is the epitope for what?

A

CA19-9

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19
Q

The A & B antigens are made from the __ antigen by the enzyme products of the ___ gene.

A
  • H antigen

- ABO gene

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20
Q

How is the A antigen formed?

A
  • A allele encodes N-acetyl-galactosaminyl transferase

- Adds N-acetyl galactosamine (NAG/Gal-NAc) to H

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21
Q

How is the B antigen formed?

A
  • B allele encodes Galactosyl transferase

- Adds D-galactose (GAL) to H

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22
Q

T/F: The O allele does not encode a functional protein.

A

True

-Group O RBCs contain abundant unaltered H antigen

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23
Q

The I and i antigens are epitopes within the ___ antigens

A

ABH

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24
Q

What represent the i antigens?

A

Unbranched type 1 and 2 oligosaccharides

25
Q

What represents the I antigens?

A

Branched type 1 and 2 oligosaccharides

26
Q

Which antigen (I or i) increases with age?

A

I (branched oligosaccharides)

*Adults have mostly I antigen

27
Q

Which antigen (I or i) predominates in neonates and cord blood?

A

i (Unbranched oligosaccharides)

28
Q

What situation might cause a resurgence of i?

A

High red cell turnovers states

29
Q

Increased postnatal i antigen expression is characteristic of what syndromes? (2)

A
  • Congenital dyserthropoietic anemia (CDA) type II

- Blackfan-Diamond syndrome

30
Q

As more A or B antigen is made, less H remains.

-Levels of H antigen (decreasing order)

A

O»A2>B>A2B>A1>A1B

31
Q

What chromosome are the A, B, and O alleles on?

A

Chr9 (long arm; q)

32
Q

When do ABO antigens 1st appear?

What age do they reach adult levels?

A
  • Fetal RBCs at 6 weeks gestation

- age 4

33
Q

Besides RBCs, where else are ABO antigens expressed? (7)

A
  • Platelets
  • Endothelium
  • Kidney
  • Heart
  • Lung
  • Bowel
  • Pancreas
34
Q

What antibodies are produced in a person with type O blood? (3)

A

IgM anti-A and Anti-B

-IgG anti-AB (can cause Mild ABO related HDFN)

35
Q

What genotypes produce the A blood group?

A

AA or AO genotype

36
Q

T/F: A1 cells express more A substance than A2.

A

True

37
Q

What percentage of blood group A individuals have the A1 phenotype?

A

80%

38
Q

A1 and A2 cells can be distinguished by the strength of reaction with what? (3)

A
  • Anti-A1 reagent (serum of group B)
  • Dolichos biflorus lectin (Anti-A1 activity)
  • Ulex europaeus (H activity; A2>A1)
39
Q

What is the most common blood group across all racial lines?

A

Group O

40
Q

The B blood group results from which genotypes?

A

BB or BO genotype

41
Q

The AB blood group results from what genotype?

A

AB genotype

42
Q

How is the Bombay phenotype made?

A

h gene (an amorph) is inherited instead of H

  • No H antigen produced in blood
  • Forms anti-H (DANGEROUS)
43
Q

T/F: The se gene is an amorph.

A

True

44
Q

What % of the population are non-secretors?

A

20% (homozygous for se/se)

45
Q

What must be present for Le(b) to be made?

A

Se and Le

46
Q

T/F: Though Lewis antigen is synthesized on free type I precursor substance, it becomes passively adsorbed onto RBC surfaces.

A

True

47
Q

The Lewis type cannot be reliably determined until what age?

A

2 years old

48
Q

What is the most common Lewis Phenotype?

A

Le(a-b+) (both whites and blacks)

49
Q

What Le phenotype is seen more often in blacks than whites.

A

Le(a-b-) (blacks 23%; whites 6%)

50
Q

When are ABO Antibodies first detected?

When do they reach adult titers?

A
  • Infants by 3-6 months

- 2 years old

51
Q

ABO incompatibility results in what?

A

Complement activation and BRISK intravascular hemolysis

52
Q

What group has Lewis antibodies?

A

Le(a-b-) (exclusively)

-Most commonly Blacks

53
Q

T/F: Lewis (a-b+) people do NOT make Le(a) antibodies.

A

True

54
Q

Lewis Antibodies are nearly always (IgG or IgM).

A

IgM (Insignificant)

55
Q

Anti-I antibodies are associated with what type of infection?

A

Mycoplasma pneumoniae

56
Q

Anti-i antibodies are associated with what type of infection?

A

EBV

57
Q

The rare significant Lewis antibody is always what?

A

Anti-Le(a)

58
Q

Why are Lewis antibodies generally insignificant?

A
  • Transfused RBCs shed their Lewis antigens and acquire the Lewis phenotype of the recipient
  • Antibodies are quickly absorbed by free serum Lewis antigens