Chapter 6 The ABO Blood Group System Flashcards
Forward grouping is defined as:
detecting antigen(s) on an individual’s red cells via reagent antisera
What percentage of the white population has type O blood?
45%
Why is reverse grouping not performed on cord blood specimens?
Antibodies are generally not present at birth
Which of the following is unique to the ABO system when compared with other blood group systems?
Individuals have antibodies to antigens they lack without foreign stimulus
How are ABH antigens formed?
production of specific glycosyltransferases add sugars to precursor substances
What immunodominant sugar is responsible for H specificity?
L-fucose
What does the hh genotype refer to?
Bombay
What is the biochemical structure of secreted A, B, and H substances?
glycoprotein
What substances are found in a group A secretor?
A, H
What is a “lectin”?
seed extracts that agglutinate human cells with moderate specificity
What percentage of the blood Type A white population is type A2?
20%
What is the source of anti-H lectin?
Ulex europaeus
What is the most important use for anti-B lectin?
differentiating a true B from an acquired-like B
All of the following are technical errors that could result in ABO discrepancies except:
a) sample misidentified
b) failure to warm reagents
c) failure to add reagents
d) clerical errors
b) failure to warm reagents
An elderly patient is documented as being type O. The forward grouping is negative with anti-A and anti-B. The reverse grouping showed no reactivity with A1 cells and B cells. What can be done to correct the discrepancy?
incubate patient serum and reagent cells for 15 minutes at room temperature
What testing is available that will differentiate between a true B and an acquired “B”?
- anti-B lectin
- acidification of anti-B reagent
- secretor studies
Reverse grouping was performed on an AB person. The technologist observed a very weak agglutination macroscopically. The cells appeared as “stacked coins” under a microscope. Which reagent should be added to the tube and recentrifuged in an attempt to resolve the discrepancy?
saline
An ABO type on a patient gives the following reactions:
Anti-A Anti-B A1 cells B cells
4+ 4+ Neg Neg
What is the patient’s blood type?
AB
The major immunoglobulin class(es) of anti-B in a group A individual is (are):
IgM
What are the possible ABO phenotypes of the offspring from the mating of a group A to a group B individual?
AB,A,B,O
The immunodominant sugar responsible for blood group A specificity is:
N-acetyl-D-galactosamine
What ABH substance(s) would be found in the saliva of a group B secretor?
slight H and B
What ABH substance(s) would be found in the saliva of a group O secretor?
heavy H only
What ABH substance(s) would be found in the saliva of a group AB secretor?
A, B, and H
