ABO System

Question 1

ABO genes are expressed _____ via ____

Answer 1

Codominantly; Mendel’s Laws of Inheritance

Question 2

Common ABO genes (4)

Answer 2

A1, A2, B, O

Question 3

Which ABO gene is an amorph?

Answer 3

O gene

Question 4

ABH Ags are predominantly ____ (sugars joined through ____ to fatty acids)

Answer 4

Glycolipids (more specifically glycosphingolipids → precursor substance); sphingosine

Question 5

Immunogenicity of ABH Ags are found in….

Answer 5

CHO portion of glycolipids

Question 6

H Ag

• Sugar
• Enzyme

Answer 6

Fucose; fucosyltransferase

Question 7

A Ag

• Sugar
• Enzyme

Answer 7

N-acetylgalactoseamine; N-acetylgalactoseaminyltransferase

Question 8

B Ag

• Sugar
• Enzyme

Answer 8

Galactose; Galactosyltransferase

Question 9

Presence of H Ags is detected with….

Answer 9

Anti-H lectin

Question 10

ABO reactivity w/ anti-H lectin

Answer 10

O > A2 > B > A2B > A1 > A1B > Oh

Question 11

Group O

• Frequency
• Ags present on RBC membrane
• Abs developed
• Compatible blood type

Answer 11

• 45%
• H Ag
• Anti-A, anti-B, anti-A,B
• O blood

Question 12

Bombay

• Ags present on RBC membrane
• Abs developed
• IAT reaction
• Compatible blood type

Answer 12

• None
• Allo-anti-H, anti-A, anti-B, anti-A,B
• Strongly positive at all phases b/c of reactivity to anti-H (screening cells are group O)
• Bombay blood

Question 13

Group AB

• Frequency
• Ags present on RBC membrane
• Abs developed
• Compatible blood type

Answer 13

• 4% (A1B 80%; A2B 20%)
• H, A, B Ags
• No Abs
• A, B, O blood

Question 14

Group A

• Frequency
• Ags present on RBC membrane
• Abs developed
• Compatible blood type

Answer 14

• 40% (A1 80%, A2 20%)
• H, A Ags
• Anti-B
• A, O blood

Question 15

Anti-A lectin
Anti-H lectin
- Use

Answer 15

Dolichos biflorus
Ulex europaeus
- Differentiate b/w A1 and A2

Question 16

Group B

• Frequency
• Ags present on RBC membrane
• Abs developed
• Compatible blood type

Answer 16

• 11%
• H, B Ags
• Anti-A
• Group B, O blood

Question 17

ABH Ags are ____ and found in ____

Answer 17

Soluble; secretions

Question 18

Presence of ABH soluble Ags depends on ____ gene

Answer 18

Secretor (Se)

Question 19

Se gene is inherited ____ from ABH genes

- if present, individual is considered a ____ and will have ABH Ags in secretions

Answer 19

Independently; secretor

Question 20

If Se is inherited, ABO type can be determined from secretions via…

Answer 20

Hemagglutination inhibition test

Question 21

Development of ABH Ags

- In fetus

Answer 21

BM; not fully developed

Question 22

Development of ABH Ags

- Detectable at…

Answer 22

6th week of gestation

Question 23

Development of ABH Ags

- Fully developed at…

Answer 23

6-18 months

Question 24

Development of ABH Ags

- After ____, Ag strength remains steady for life

Answer 24

Age 3

Question 25

ABH Abs form in response to ____ stimuli

Answer 25

Environmental ("naturally occurring")

Question 26

Anti-A and anti-B | - Ig class

Answer 26

IgM

Question 27

ABH Abs | - Origin

Answer 27

- Transfusion of incompatible RBCs - Pregnancy (leakage of incompatible fetal cells into mom's circulation) - Vaccinations (some contain A and B soluble substances)

Question 28

Development of ABH Abs | - At birth

Answer 28

No Abs formed yet | - Any detectable Abs are of maternal origin

Question 29

Development of ABH Abs | - 3-6 months of age

Answer 29

Detectable amounts

Question 30

Development of ABH Abs | - Ages 5-10 years old

Answer 30

Highest titers, then gradually decreases (unnoticeably)

Question 31

Anti-A,B | - Ig class

Answer 31

50/50 w/ respect to IgG and IgM | - Common cause of HDFN

Question 32

``` Serologic reactivity of ABH Abs - Optimal temperature - Detected at ____ AHG stage - Cross placenta? Bind to complement? ```

Answer 32

- Room temp or colder (4C enhances IgM; 37C and AHG due to IgG component) - Immediate sprin - Does not cross placenta - Bind C' (causes hemolysis)

Question 33

Front typing/Forward Grouping/Cell Typing | - Un/known Ag and un/known Ab source

Answer 33

Ab source: reagent antisera (known) | Ag source: patient RBCs (unknown)

Question 34

Back typing/Reverse Grouping/Serum Typing | - Un/known Ag and un/known Ab source

Answer 34

Ag source: Reagent RBC (known) → A1 and B cells | Ab source: patient serum (unknown)