ABO Blood Groups Flashcards
Most important blood group system
ABO
Only blood group system in which individuals already have antibodies in plasma to antigens that are absent from red cells without prior exposure
ABO blood group system
What are the 4 major phenotypes of the ABO blood group system?
A
B
AB
O
What controls the major phenotypes of the ABO blood group system?
2 co-dominant genes on chromosome 9
What is Group O considered?
An amorph
Group B will build what antibodies?
anti-A
Group A will build what antibodies?
Anti-B
Group AB will build what antibodies?
None
Group O will build what antibodies?
Anti-A and Anti-B
What are 2 ways to be exposed to IgG antibodies?
-Through pregnancy (female)
-Previous transfusion
Major glycoprotein of the red cell membrane
Glycophorin
Glycophorin accounts for most of the ________ _______ that gives cells the negative charge
Sialic acid
What are the ABO sugars added to what on the cell membrane?
Carbohydrates
When are ABO antigens detectable ?
As early as 5 weeks in utero
Full expression of ABO antigens occurs at what age?
2-4 years
Most common ABO blood type
O
Rarest ABO blood type
AB
Possible genotypes for Group A phenotype
AA or AO
Possible genotypes for Group B phenotype
BB or BO
Possible genotype for Group AB phenotype
AB
Possible genotype for Group O phenotype
OO
What are the formations of A and B antigens is dependent on?
H antigen
What antigens are transferases?
ABH
Definition:
Transfer a certain carbohydrate to a glycolipid precursor on the RBC membrane
Transferases
What does the H gene produce?
L-fucose
Carbohydrate that extends off the RBC membrane and is composed of various sugars
Oligosaccharide chain
Type 1 oligosaccharide chains are found where?
Body fluids and secretions
Type 2 oligosaccharide chains are found where?
Red blood cells, body fluids, and secretions
H gene produces a transferase that transfers what to this substrate on the membrane?
Fucose
H antigen transferase name
L-Fucosyltransferase
H gene immunodominant sugar
L-Fucose
A patient that doesn’t have the H antigen (genotype hh) is known as having what phenotype?
Bombay phenotype
A antigen transferase
N-Acetylgalactosominyltransferase
Group A antigen immunodominant sugar
N-Acetylgalactosamine
B antigen transferase
D-Galactosyltransferase
B antigen immunodominant sugar
D-Galactose
Which ABO blood type has the greatest amount of H antigen?
Group O
H antigen concentrations in ABO phenotypes:
Put in order - A1, B, A1B, A2, A2B, O
O > A2 > B > A2B > A1 > A1B
Another name for ABO antibodies
Isoagglutinins
TRUE or FALSE:
ABO antibodies are always clinically significant
TRUE
At what age are ABO antibodies produced?
3-6 months
A,B is of what antibody classification?
IgG
What % of Group A people are of subgroup A1?
80%
What % of Group A people are of subgroup A2?
20%
Is subgroup A2 more efficient or less efficient at converting H to A?
Less efficient
What % of people who are A2 produce an anti-A that reacts with A1 cells but not A2 cells?
1-8%
A1 has what type of molecular structures?
Linear and branched
A2 has what type of molecular structures?
Linear
Which A subgroup demonstrates mixed field agglutination?
A3
Where antigens are located
On the red cells
Where antibodies are located
In the serum/plasma
What is known and unknown in the forward typing?
Known: antibody
Unknown: antigen
Reagents used in the forward typing
Commercial anti-sera
-Anti-A
-Anti-B
-Anti-A,B
Patient’s red cells
What is a positive forward type reaction?
Agglutination - means the antigen is present
What is known and unknown in the reverse typing?
Unknown: antibody
Known: antigen
Reagents used in back/reverse typing
-Commercial A and B red cells
-Patient’s serum
TRUE or FALSE:
If a patient specimen reacts with commercial B cells their blood type is considered Group B
FALSE - patient has antibodies to the B antigen meaning they are either Group A or Group O
What blood type could a patient be if their specimen agglutinates with commercial A cells?
Group O or Group B
Antibodies present if patient is Group A
Anti-B
Antibodies present if patient is Group B
Anti-A
Antibodies present if patient is Group O
Anti-A and Anti-B
Antibodies present if patient is Group AB
No antibodies
If a patient has A antigens, what is their blood type?
Group A
If a patient has A and B antigens, what is their blood type?
Group AB
If a patient has no antigens, what is their blood type?
Group O
Grading agglutination:
One solid aggregate of red cells
4+
Grading agglutination:
Several large aggregates
3+
Grading agglutination:
Medium-size aggregates, clear background
2+
Grading agglutination:
Small aggregates; turbid, reddish background
1+
Grading agglutination:
Tiny aggregates; turbid, reddish background
W+
Grading agglutination:
Microscopic aggregates only
Circled + sign
Grading agglutination:
Negative or no aggregates
= or 0
Antibody-like substance derived from the extract of a plant seed
A1 Lectin
What plant is A1 Lectin derived from?
Dolichos biflorus
If you do a forward typing and use A1 Lectin, what must you also use in the reverse typing?
A2 red cells
What blood group would have this reaction?
Group A1
What blood group would have this reaction?
Group B
What blood group would have this reaction?
Group A1B
What blood group would have this reaction?
Group O
What blood group would have this reaction?
Group A2
What blood group would have this reaction?
Group A2B
