ABO BLOOD GROUP SYSTEM (001) Flashcards by Janus Palermo

He discovered the ABO blood group in 1901

Karl Landsteiner

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ABO gene is expressed in chromosome ___:

Chromosome 9

note: encodes for an enzyme that adds sugar to a precursor substance

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H gene is expressed in chromosome ____:

Chromosome 19

note: Formation of H antigen = “biosynthetic precursor” for formation of A & B antigens

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The Secretor gene is expressed in chromosome ____:

Chromosome 19

note: expression of ABH Ag on body secretions/fluids

Body fluids where ABH antigens can be detected:
- Salive
- Tears
- Urine
- Digestive juice
- Bile
- Milk
- Amniotic fluid
- Pleural
- Peritoneal
- Pericardial fluids

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Secretor gene that represents the homozygous dominant genotype:

SeSe

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Secretor gene that represents the heterozygous dominant genotype:

Sese

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Non-secretor gene:

sese

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Immunodominant sugar of H gene:

L-fucose

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Glycosyltransferase of H gene/H antigen

a-2-L-fucosyltransferase

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Glycosyltransferase of A gene/A antigen

a-3-N-acetylgalactosaminyltransferase

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Glycosyltransferase of B gene/B antigen

a-3-D-galactosyltransferase

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Immunodominant sugar of A antigen:

N-acetyl-D-galactosamine

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Immunodominant sugar of B antigen:

D-galactose

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H antigen has an incidence rate of:

> 99.99%

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Formation of antigens occurs in the ____ day of fetal life

37th day of fetal life

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Antibodies synthesization:
Start:
Peak:

Antibodies synthesization:
Start: 3-6 months old
Peak: 5-10 years old

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Laboratory detection procedure of antigen:

Forward/Cell typing

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Reagents used for forward/cell typing:

Anti-A (trypan blue dye)
Anti-B (acriflavine dye)

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Laboratory detection procedure of antibodies:

Reverse/Serum Typing

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Reagents used for Reverse/Serum typing:

Red cell suspensions of:
- A1 cells (known A)
- B cells (known B)

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ABO reactions

Type A (AA, AO)

FORWARD
Anti-A =
Anti-B =

REVERSE
A1 cells =
B cells =

ABO reactions

Type A (AA, AO)

FORWARD
Anti-A = 4+
Anti-B = 0

REVERSE
A1 cells = 0
B cells = 4+

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ABO reactions

Type B (BB, BO)

FORWARD
Anti-A =
Anti-B =

REVERSE
A1 cells =
B cells =

ABO reactions

Type B (BB, BO)

FORWARD
Anti-A = 0
Anti-B = 4+

REVERSE
A1 cells = 4+
B cells = 0

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ABO reactions

Type AB (AB)

FORWARD
Anti-A =
Anti-B =

REVERSE
A1 cells =
B cells =

ABO reactions

Type AB (AB)

FORWARD
Anti-A = 4+
Anti-B = 4+

REVERSE
A1 cells = 0
B cells = 0

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ABO reactions

Type O (OO)

FORWARD
Anti-A =
Anti-B =

REVERSE
A1 cells =
B cells =

ABO reactions

Type O (OO)

FORWARD
Anti-A = 0
Anti-B = 0

REVERSE
A1 cells = 4+
B cells = 4+

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A homozygous gene considered to be amorph or silent, does not code for production of antigen:

Homozygous O gene (type O)

What is the test principle for determining secretor property?

Hemagglutination inhibition

Specimen of choice for determination of secretory property:

Saliva (source of ABH-soluble antigens)

Results/interpretation of determination of secretory property:

Agglutination = individual is non-secretor (negative) No agglutination = individual is secretor (positive)

Determines the possible blood type of an offspring with the use of a Punnett square:

`ABO mating

Weak A subgroups:

A1 A2

Most prevalent A subgroup

Antigen present in A1 subgroup

A and A1

A1 subgroup reaction with Anti-A1 Lectin

4+ agglutination

Unexpected Antibody present in A2 subgroup:

Anti-A1 (1-8%)

A2 subgroup reaction with Anti-A1 Lectin

0 (no agglutination)

Seed extracts that can agglutinate human cells with some degree of specificity:

Lectins

Anti-A1 Lectin source:

Dolichos biflorus

Anti-H Lection source:

Ulex europeus

Anti-M Lectin source:

iberis amara/ Macluara aurantiaca

Anti-N Lectin source:

Vicia graminea

Absence of H gene causes non-expression of ABH antigens

Bombay Phenotype

Bombay Phenotype characteristics in RBCs = Serum =

Bombay Phenotype: RBCs = absence of ABH antigens Serum = presence of Anti-A, Anti-B, Anti-AB and Anti-H Anti-A, B, and AB - same Abs found in type O individuals, Anti-H - unique in Bombay phenotype

What type of immunoglobulin antibody is Anti-H?

IgM antibody agglutinates at 4-22C (room temperature) hemolysis due to C' fixation at 37C

Bombay phenotype symbols include:

hh, Oh, Hnull

Inherited genes and their corresponding antigens HH AO Se Se RBC Ag present: Secretion antigen present:

HH AO Se Se RBC Ag present: H, A Secretion antigen present: H, A

Inherited genes and their corresponding antigens Hh BO sese RBC Ag present: Secretor Ag present:

Inherited genes and their corresponding antigens Hh BO sese RBC Ag present: H, B Secretor Ag present: none

Inherited genes and their corresponding antigens hh AB sese RBC Ag present: Secretor Ag present:

Inherited genes and their corresponding antigens hh AB sese RBC Ag present: none Secretor Ag present: none Note: - No RBC Ag is present because there is no precursor substance (H antigen) - This is an example of the Classical Bombay Phenotype

Anti-H Lectin reaction with Oh/Bombay phenotype:

0 (no reaction)

Bombay phenotype reaction to O cells:

4+ - because of the presence of Anti-H in Bombay serum

Occur when unexpected reactions occur in the forward and reverse grouping; all technical factors should be reviewed and corrected to resolve the discrepancy:

ABO Typing Discrepancies

Group I Discrepancy:

Missing or Weakly reacting Antibody

Group II Discrepancy:

Missing or weakly reacting Antigen

Group III Discrepancy:

Plasma protein abnormalities

Group IV Discrepancy:

Miscellaneous problems

Problem in Group I discrepancy:

Problem in Reverse Typing

Examples of Group I Discrepancy:

1. Newborns, elderly patients 2. Agammaglobulinemia 3. Hypogammaglobulinemia 4. Dilution of ABO antibodies

problem in Group II Discrepancy:

Problem in Forward typing

Examples of Group II Discrepancy:

1. Leukemia, Hodgkin's disease 2. A/B Subgroups 3. Acquired B phenomenon 4. Excessive amount of BGSS

Problem in Group III Discrepancy:

Rouleaux formation; common in REVERSE typing

Examples of Group III Discrepancy:

1. Multiple Myeloma 2. Waldenstrom's 3. Elevated fibrinogen levels 4. Wharton's Jelly

Problem in Group IV Discrepancy:

Problem in either FORWARD or REVERSE or BOTH

Examples of Group IV Discrepancy:

1. Cold-reactive autoantibodies 2. Unexpected antibodies 3. Cis-AB

Describe what group discrepancy: Anti-A = 4+ Anti-B = 0 A1 cells = 0 B cells = 0 O cells = 0 AC = 0

Group I Discrepancy - missing/weakly reacting antibody

Describe what group discrepancy: Anti-A = 0 Anti-B = +/- A1 cells = 4+ B cells = 0 O cells = 0 AC = 0

Group II Discrepancy - missing/weakly reacting antigen

Describe what group discrepancy: Anti-A = 4+ Anti-B = 2+ A1 cells = 0 B cells = 4+ O cells = 0 AC = 0

Group II Discrepancy - Acquired B phenomenon Cause: Bacterial modification of sugar on A antigen that is associated in GI infection/obstruction; the N-acetyl part in N-acetyl-galactosamine is removed by bacteria. The remaining galactosamine becomes the modified sugar and acts as "Pseudo-B" antigen and causes the reaction to anti-B

Describe what group discrepancy: Anti-A = 4+ Anti-B = 4+ A1 cells = 2+ B cells = 2+ O cells = 2+ AC = 2+

Group III Discrepancy - Rouleaux formation Note: rouleaux formation causes pseudo agglutination; this can also be the caused by Wharton's Jelly

Describe what group discrepancy: Anti-A = 2+ Anti-B = 4+ A1 cells = 4+ B cells = 2+ O cells = 2+ AC = 2+

Group IV Discrepancy - cold reactive autoantibodies note: IgM abs that causes clumping of RBCs @ 4-22C (room tenp) associated with Mycoplasma pneumonia = cold agglutinins

Resolution/remedy for Group I discrepancy (missing/weakly reactive Ab)

Extend the incubation time of reverse typing mixture for 15-30 minutes at room temperature

Resolution/remedy for Group II discrepancy (missing/weakly reactive Ag)

Extend the incubation time of forward typing mixture for 15-30 minutes at room temperature

Resolution/remedy of Group II discrepancy (Acquired B phenomenon)

1. Acidify AntiB reagent 2. Secretor studies 3. Addition of acetic anhydride to patient red cells (re-acetylates the sugar of A antigen)

Resolution/remedy for Group III discrepancy (Rouleaux formation)

Saline dilution/washing of RBCs Wash cord cells with NSS for 6-8x to remove Wharton's Jelly (cause of discrepancy)

Resolution/remedy for group Iv discrepancy (cold-reactive autoantibodies)

1. Prewarming of test components at 37C 2. Add sulfhydryl reagents (DTT, 2-ME) ---> destroys IgM 3. Adsorb cold-reactive antibodies using RESt (Rabbit erythrocyte stroma)

ABO BLOOD GROUP SYSTEM (001) Flashcards

memorization (72 cards)