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Blood Bank: Spring 2024 > ABO Blood Groups Pt 2 > Flashcards

ABO Blood Groups Pt 2 Flashcards

1
Q

Relate secretor status to Bombay antigen expression in ABO and Lewis families

A
  • Genes: hh, sese, unknown ABO, Le
  • Ab: anti-A, anti-B, anti-H, anti-A,B
  • Ag: Lewis a (Lea)
  • Secretions: Lewis a
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2
Q

Relate secretor status to Parabombay antigen expression in ABO and Lewis families

A
  • Genes: hh, SeSe, A or B
  • Ab: anti-A or anti-B
  • Ag: Lewis b (Leb), small amount of Lea, small amount of absorbed A or B
  • Secretions: A or B
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3
Q

Describe how secretor status affects presentation of Lewis and ABH antigens on RBC and in secretions

A
  • A secretor does not have to have H antigen (can be hh like Parabombay)
  • Must be SeSe or Sese to be secretor bc need functional FUT2 to add terminal fucose to Type 1 precursor chain
  • Must be LeLe or Lele bc need FUT3 to add non-terminal fucose, thus making Leb
  • Only Leb can be secretor, not Lea, bc only it has the terminal fucose from FUT2
  • Can express A or B and thus secret A or B
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4
Q

What is the clinical significance of Lewis Ab in patient plasma to ABO Ab in patients plasma?

A

Testing the Lewis Ab in patient plasma combined with testing the ABO Ab in patient plasma helps to get a more complete picture interpretation, such as if they’re Bombay, Parabombay, or a normal secretor

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5
Q

Is a person who has Lea on their RBCs secretor or non-secretor? Genotype?

A
  • Non-secretor
  • sese
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6
Q

Is a person who expresses Leb on their RBCs a secretor or non-secretor? Genotype?

A
  • Secretor
  • Sese or SeSe
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7
Q

How are secretions formed biochemically? Hint: Le(a-b+)

A
  1. FUT2 (Sese or SeSe) gene codes for fucosyl transferase that adds Fucose to Type 1 precursor chain
  2. FUT3 (Lele or LeLe) gene encodes for another transferase that adds fucose to the non-terminal end of the Ag in secretions only
  3. Leb formed!
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8
Q

How are non-secreted substances formed? Hint: Le(a-b-)

A
  1. FUT2 doesn’t add fucose to terminal sugar to make H-antigen but FUT3 still adds its non-terminal fucose to create Lea
  2. Expressed on RBCS that are non-secretors
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9
Q

Why do Leb positive pt not make anti-Lea?

A

Secretors make a little bit of Lea while mostly making Leb

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10
Q

Genotype for person with no lewis antigens (negative for FUT3)

A

lele

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11
Q

Can an lele person still secrete ABH antigens? Why or why not?

A

Yes, because different genes encode them

H/h = FUT1 gene (encodes H Ag)
Se/se = FUT2 gene
Le/le = FUT3 gene
AB = ABO gene

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12
Q

Alleles for FUT1 and protein the gene encodes

A
  • H/h
  • Fucose on terminal sugar of Type 2 precursor chain to make H antigen
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13
Q

Alleles for FUT2 and protein the gene encodes

A
  • Se/se
  • Fucose on terminal sugar of Type 1 precursor chain to make H antigen
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14
Q

Alleles for FUT3 and protein the gene encodes

A
  • Le/le
  • Lewis a (non-secretor) or Lewis b (secretor)
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15
Q

List the positive and negative controls for anti-A1 lectin

A
  • Positive control: A1 cells
  • Negative control: A2 cells (or B cells but non-specific to lectin function)
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16
Q

Name of guy who discovered ABO typing system

A

Landsteiner

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17
Q

T/F
ABO was the first genetic marker used in forensic and paternity testing

A

True

18
Q

Discrepancy

A

When forward and reverse typing results don’t agree on the same blood type

19
Q

What is the most common ABO discrepancy? How do you solve it?

A

Missing reactivity
Solve by cooling bc IgM Ab react best at cold temp

20
Q

How do you solve a serological test where there’s too much reactivity?

A
  • Warm the patient plasma (rvs)
  • Wash patient RBCS (fwd)
  • Test against O screen cells
21
Q

What are A and B subgroups?

A
  • Weak expressions of A or B Ag on patient RBCs
  • Forward type
22
Q

T/F
You can use B1 lectin to assess B subgroups

A

False, B1 lectin does not exist

23
Q

T/F
You can use anti-A2 Ab to assess a patient’s A subgroup status

A

False, anti-A2 doesn’t exist

24
Q

T/F
Weak expression of Ab has more to do with a pt’s immune status than their subgroup status

A

True

25
Q

When should you consider the possible existence of a subgroup?

A

If there is extra Ab expression

26
Q

When should you add anti-A1 lectin to patient RBCS?

A

When the pt has weak A expression
Want to see if they’re A2

27
Q

When should you add A2 cells to patient plasma?

A

When the pt has an extra reaction with A1 cells (anti-A1 present in pt plasma even though anti-A Ab identified them as Type A or AB)

28
Q

When should you add anti-A,B Ab to patient RBCS?

A
  • When the patient has weak or missing reactions with anti-A or anti-B
  • anti-A,B targets a broader spectrum of Ag sites that anti-A or anti-B may not catch
29
Q

When should you add screen cells (Type O) with patient plasma?

A
  • When the pt has extra Ab activity that may be related to A or B Ag
  • Looking for Lewis Ag
30
Q

When should you use patient cells against patient plasma?

A

When the pt has extra Ab activity that may be related to all other cells
?????

31
Q

Which blood type is the universal RBC donor and why?

A

Type O because recipient won’t have Ab against it
Universal plasma recipient

32
Q

Which ABO type is the universal plasma donor and why?

A

Type AB because it contains no antibodies against any of the other types
Universal RBC recipient

33
Q

What % donors can give A plasma in trauma situation?

A

85%
Type AB plasma also okay bc universal plasma donor (no Ab made)

34
Q

Describe naturally occurring antibodies

A
  • Found in plasma of ppl who have not been previously exposed to RBCS through transfusion or pregnancy
  • Formed early in life and may persist
  • Usually IgM
  • Questionable clinical significance
  • May be non-specific or reactive to variety of immune stimuli
  • e.g., anti-A, anti-B, anti-H
35
Q

Choose the answer that is false about ABO Ab:
A. Fix complement
B. Cold reacting at room temp
C. IgG for most part
D. Strength of Ab decreases in some disease states and old age

A

C
The correct answer is IgM for most part

36
Q

Describe immune-stimulated Ab

A
  • Made by pt after exposure to RBCs via transfusion or pregnancy
  • Formed later in life and may grow dormant/serologically undetectable
  • Usually IgG
  • Often indicates ability to have reaction if exposed again
  • May be specific
  • e.g., anti-D, anti-Lea
37
Q

Draw Type 1 or Type 2 precursor chain

A
38
Q

Draw H antigen

A

D

39
Q

Draw Lewis b Ag

A
40
Q

Draw Lewis a Ag

A
41
Q

Draw A Ag

A
42
Q

Draw B Ag

A

Blood Bank: Spring 2024 (10 decks)

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