Antibody Identification Flashcards
What is the purpose of an antibody screen?
To detect RBC antibodies other than anti-A and anti-B
What type of antibodies are detected in an antibody screen?
Unexpected antibodies (0.3-2% of the general population has them)
What causes an antibody to be significant?
The ability to shorten RBC survival
What test requires testing patient serum against screening cells that contain known antigens?
Antibody screen
Screening cells are of which ABO group?
Type O
Why are group O cells used in screening cells?
So a patient’s anti-A and/or anti-B will not interfere with the detection of significant unexpected antibodies
Term for the list of the antigen makeup of each cell provided with each lot of screening cells issued from a manufacture
anti-gram
Ideal screening cells have what type of expression of as many antigens as possible?
homozygous expression
Homozygous antigen expression on screening cells is especially helpful when antibodies, such as anti-Jk and anti-M, show what?
dosage
What may be a reason a significant antibody goes undetected even though the procedures were followed correctly?
dosage. Some antibodies will only show visible reactions when a cell is homozygous for its corresponding antigen
A single vial form of screening cells contains…
No more than 2 donor cells pooled together
A two vial form of screening cells contains
2 donors, each in a separate vial
A three vial form of screening cells contains…
3 different donors, each in a separate vial
The degree of a positive reaction typically indicates…
the amount of antibody present, not its significance
What is it called when a patient’s serum is tested against the patient’s RBCs?
autologous control
If an autologous control is positive, what other test would you expect to also be positive?
DAT
When should agglutination tests be read and why?
directly after centrifugation. Any delay in time can cause the antibodies to elute from the antigens and result in a false-negative.
Which immunoglobulin class reacts best at cold temperatures and is capable of causing agglutination with cells suspended in saline?
IgM
Which immunoglobulin class reacted best at AHG phase of testing?
IgG
A positive antibody screen and a negative autologous control indicates the detections of an
alloantibody
A positive antibody screen and a positive autologous control indicates the detection of an
autoantibody
What can cause a positive autologous control due to an alloantibody?
recent transfusion
Name 2 situations where non-specific agglutination can occur
Multiple myeloma patients and patients on plasma expanders
Rouleaux will only interfere with which phase of testing and why?
Rouleaux only interferes with the IS phase, not the AHG phase because the patient’s serum is washed away before the AHG phase
What can be used to disperse rouleaux?
1-3 drops of saline
