IS BLOOD TYPING Flashcards
Who Identified the presence of
2 separate erythrocyte Ags (A&B Ags).
Karl Landsteiner (1900)
He later proposed 3 separate groups
- Karl Landsteiner
- he later proposed 3 groups A, B, & O.
Who Identified the 4rth group (AB)
von Decastello & Sturli
Amorphic: no detectable Ag is produced
in response to the inheritance of this gene.
Blood type O
who discovered 4-allele theory of inheritance?
The 4-allele theory are the ff:
- Thompson
- A1,A2,B and O.
2 subgroups of A
A1 and A2
T or F: H gene is inherited
True
H gene codes for the production of _______
that catalyzes the addition of _______ the immunodominant structure of ______ to two slightly different structures known as the _____ and ______
- α-L- fucosyl transferase
- L-fucose
- H antigen
- type 1 & 2 precursor chains.
Expression of H, A, and B Ags:
Gene
H
A
B
O
H- α-L-fucosyltransferase
A- α-3-N-acetyl-D-galactosaminyl transferase
B- α-3-D galactosyl transferase
O- None
Classification of the ABO blood
SERUM ANTIBODIES:
A
B
AB
O
A - Anti-B
B - Anti-A
AB - None
O - Anti-A, Anti-B, Anti- A,B
RXNS OF PATIENT ERYTHROCYTE & REAGENT ABs
Blood Group:
A
B
AB
O
A : anti A (Positive) Anti B (Negative)
B - Anti A (Negative) Anti B (Positive)
AB - Anti A (Negative) Anti B (Negative)
O - None
The major abo genotypes &
phenotypes
PHENOTYPE: A1, A2, A1B, A2B, B, O
GENOTYPE:
A1 - A1/A1, A1/A2, A1/O
A2 - A2/A2, A2/O
A1B - A1/B
A2B - A2/B
B - B/B, B/O
O - O/O
The assortment of antigens
actually detectable on an individual’s red
cells using selected antisera. In many blood
group systems, the _______ is an exact
expression of the genotype.
PHENOTYPE
The sum of all genes a person has
inherited within a blood group system.
GENOTYPE
A series of Ags exhibiting the same serological & physiological characteristics, & inherited according to specific patterns.
BLOOD GROUP SYSTEM
Representative ABO frequencies
(Mourant)
A1
A2
B
A1B
A2B
O
A1: W- 32% B-19% O- 27%
A2: W- 9% B-8% O- (Rare)
B: W- 9% B-19% O- 25%
A1B: W- 3% B-3% O- 5%
A2B: W- 1% B-1% O- (Rare)
O: W- 45% B-49% O- 40%
Serologic distinction between A1 & A2 Ags is based on the
reactions of erythrocytes w/
various anti-sera.
full name of lectin anti-A1
(Dolichos biflorus seeds).
Lectin anti-A1 agglutinates in ___ but not in ___
A1, A2 erythrocytes.
What are lectins?
Seed extracts that agglutinate human cells
with some degree of specificity.
What are some of the lectins? and how and when do they agglutinate?
- Dolichos biflorus: agglutinates A1 or A1B
- Bandeiroea simplicifolia: agglutinates B cells
- Ulex europaeus: agglutinates O cells (H
specificity) and other ABO blood groups
depending on the amount of H Ag available.
Characteristics of Antisera: Anti-A reagent
Monoclonal Ab
Highly specific
IgM
Clear blue colored reagent
Expected 3+ to 4+ reaction
Usually use 1-2 drops
Characteristics of Antisera: Anti-B reagent
Monoclonal Ab
Highly specific
IgM
Clear yellow colored reagent
(contains an acriflavine dye)
Expected 3+ to 4+ reaction
Usually use 1-2 drops
Discrepancies in abo forward
grouping (False (+) results)
1.Contaminated reagents or dirty glassware
2. Overcentrifugation
3. Incorrect interpretation or recording of tests results
Discrepancies in abo forward
grouping (False (-) results)
- Lack of specimen or reagents in the test system
- An incorrect serum: cell ratio
- Undercentrifugation or incorrect incubation
temperature - Old or otherwise inactive reagents
- Incorrect interpretation, such as failure to
recognize hemolysis as a (+) reaction, or an error in
the recording of test results
Other sources of technical errors
- Inadequate identification of blood specimens, test tubes or slides.
- Cell suspension either too heavy or too light.
- Clerical errors
- A mix-up samples
- Failure to follow manufacturer’s instructions.
- Uncalibrated centrifuge
IF carefully controlled repeat testing yields the same agglutination patterns, the variation can be assigned to one of 4 categories:
- Weak or missing antigen reactions
- Unexpected antigen reactions
- Weak or missing antibody reactions
- Unexpected antibody reactions
How do you make the cell suspension
3-5% red cell suspension
Reporting of Results
Agglutination of RBCs in the presence of
reagent is a positive test result and indicates the presence of the corresponding antigen.
Negative control should have a negative
result; otherwise, further investigation and
testing must be considered.
