Unit 2 ABO Blood Group Flashcards
Who discovered the ABO blood group system?
Karl Landsteiner in 1901
What is detected in reverse grouping?
Naturally occurring antibodies
What antigen serves as the precursor for A and B antigens?
H antigen
What antigens are present in a group B individual?
B antigen
What antibodies are present in a group O individual?
Anti-A, Anti-B, Anti-AB
What is the ISBT number for the ABO blood group?
ISBT 001
What is the ISBT number for the Rh blood group?
ISBT 004
Which blood type is the universal donor for red cells?
Blood group O
Which blood type is the universal donor for plasma?
Blood group AB
Which blood type is the universal recipient of red cells?
Blood group AB
Which blood type is the universal recipient of plasma?
Blood group O
What does forward typing detect?
Unknown antigen using known antibody
What does reverse typing detect?
Unknown antibody using known antigen
Why is reverse typing not required for babies?
They still have no antibodies
Which phenotype is most likely to have an ulcer?
O phenotype
Which phenotype is most likely to have gastric carcinoma?
A phenotype
Which phenotype is most likely to have criminal instincts?
B phenotype
What type of antibodies are ABO antibodies?
Naturally occurring IgM
Which ABO antibody contains IgG?
Anti-AB
What is required to activate complement in ABO antibodies?
Only one IgM molecule
At what temperature do ABO antibodies react?
Room temperature or colder
When does ABO antibody production begin?
At birth
At what age do ABO antibody levels peak?
Between 5-10 years old
Why do elderly individuals have lower antibody levels?
Thymus decreases in size with age
What is the difference between genotype and phenotype?
Genotype is inherited, phenotype is expressed
What does the H gene do?
Produces antigens on red blood cells
What does the Se gene do?
Produces antigens in secretions
What is the probable phenotype if a child inherits AO genotype?
A blood type
Which genes are dominant in ABO inheritance?
A and B
Which gene is recessive in ABO inheritance?
O
What is the precursor for ABO antigens?
Paragloboside or glycan
What is the immunodominant sugar for the H antigen?
L-fucose
What is the immunodominant sugar for the A antigen?
N-acetyl-D-galactosamine
What is the immunodominant sugar for the B antigen?
D-galactose
Which blood group has the highest antigen sites?
A1 adult RBCs (810,000-1,170,000 sites)
How many antigen sites does a B adult RBC have?
610,000-830,000 sites
Which gene codes for the B antigen transferase?
B gene (α-3-D-galactosyltransferase)
Why do AB individuals have more B antigens than A antigens?
B enzyme is more efficient in conversion
Where are ABH antigens found?
RBCs, endothelial cells, platelets, lymphocytes, epithelial cells
Where are ABH soluble antigens found?
All body secretions
What is required for ABO typing in organ transplants?
Both ABO typing and HLA typing
What is the genotype for a classical Bombay phenotype?
hh sese (no H antigen, no secretions)
What enzyme does the Se gene code for?
α-2-L-fucosyltransferase
What does agglutination inhibition testing check?
Secretion of ABH substances
What is the sugar responsible for H specificity?
L-fucose
What is the rare genotype that results in the Bombay phenotype?
hh
Which gene is more common, H or h?
H gene is present in >99.99% of the population
How can acquired B phenotype occur?
E. coli 086 infection removes N-acetyl from A antigen
How does the Se gene affect secretions?
Allows A and B antigens to be present in secretions
What is the primary structural difference between ABH antigens in RBCs and secretions?
RBC antigens are glycolipids/glycoproteins, secretions are glycoproteins
What linkage is found in type 2 precursor chains (RBCs)?
β1 → 4 linkage
What linkage is found in type 1 precursor chains (secretions)?
β1 → 3 linkage
What is the function of α-2-L-fucosyltransferase?
Adds L-fucose to the precursor chain to form H antigen
