detection and Identification of Antibodies Flashcards
What determines if a red blood cell antibody is clinically significant?
Shortened RBC survival
What is tested in an antibody screen?
Patient serum is tested against group O reagent screening cells
Why are screening cells group O?
To prevent interference with anti-a or anti-b in patient serum
Antibodies in which of the following blood group systems are “notorious” for escaping detection on an antibody screen and cause a severe delayed hemolytic transfusion reaction when antigen positive red blood cells are transfused to a patient?
Kidd
What screening cells are used primarily for testing donor units for unexpected antibodies?
Pooled
Why might some blood banking facilities prefer the use of monospecific IgG over polyspecific antihuman globulin (AHG) in their antibody screens?
Interference from naturally occurring cold antibodies in patient sera is reduced
Which of the following is known as the “sensitization phase” in the antibody screen?
37 degrees C incubation
What makes up an autologous control?
Patient serum and patient cells
A positive autocontrol in antibody detection procedures is usually indicative of:
Positive DAT
What might a positive antibody screen and a negative autocontrol indicate?
An alloantibody has been detected
When should multiple antibodies be suspected in a positive antibody screen?
Cells react and different phases and strengths
In what test might rouleaux cause an interference?
Reverse ABO grouping
Why is it important to match the lot number on the panel sheet with the lot number on the panel cells?
Pattern of reactions will change from lot to lot
Why should only homozygous cells be used to rule out an antibody?
Weakly reacting antibody may not react with heterozygous cells
If you suspect anti-C is present in a patient’s serum, and anti-Fya still has to be ruled out using other reagent cells, what would the phenotype of the rule out cell have to be?
Fy (a+), C-, Fy (b-)
How would 4 units of red blood cells be found for a patient with antibodies to C, Fya, and Jkb?
random crossmatching patient’s sera followed by phenotyping compatible units of red blood cells
your blood supplier
Tests with which AHG reagents can determine if IgG, complement, or both are coating red blood cells?
monospecific
Which of the following is a mechanism of an elution procedure?
Disruption of structural complementarity of antigen and antibody
What is the most common use of adsorption?
Removal of autoantibody from patient serum
In what circumstances would an alloadsorption be performed?
Multiple antibodies in patient serum
How can neutralization aid in the identification of multiple antibodies?
Once antibody has been neutralized serum can be further tested in panel studies
What test is used to confirm efficacy of chloroquine treatment?
DAT
Why are antibodies to high-frequency antigens, such as cellano (k), rarely seen in patient samples?
Most persons are not antigenically stimulated to produce the antibody because their red blood cells are positive for the antigen
What would be a realistic source of finding compatible units for a person with an antibody to a high-frequency antigen?
Siblings
Which of the following high-frequency antigens do not cause in vivo red blood cell destruction when complexed with corresponding antibody?
Cha
Which of the following statements are correct concerning cold antibody screens?
Patient serum is incubated with group O red blood cells at 4 degrees C
A person has developed an antibody to the LISS reagent. What test will not be affected by this circumstance?
DAT
Why can’t autoadsorption be performed on a patient who was transfused 1 month before?
Donor cells might adsorb out alloantibody in serum
What is the purpose of treating serum containing cold autoantibodies with dithiothreitol (DTT) or 2-mercaptoethanol (2-ME)?
To denature IgM cold autoantibody and test serum for presence of IgG alloantibody
What test must be performed on a patient with a warm autoantibody in their serum before transfusing?
Warm autoadsorption
