Ab Screen & ID Flashcards
what does an ab screen detect
unexpected allo or auto abs
what kind of sample is used in an ab screen
sera or plasma
what are the 3 testing phases of an ab screen
IS, 37 C, and AHG (Coombs)
what kind of cells are ab screening cells
group O
what kind of ab screen uses pooled ab screening cells
donor testing
what kind of ab screen uses 2 or 3 cell ab screening cell
pt testing
what is the standard ab screening cells used today
3 cell screening
why are 3 cell screening cells used
guarantees homozygosity in the blood groups
what are the 4 currently acceptable ab screening test methods
tube, gel, solid phase red cell adherence, and microwell
what is the standard ab screening test method
tube
what kind of reagent is used in an ab screen
monospecific with anti IgG
what does enhancement media contain in an ab screen
22% albumin, LISS, PEG
what is the normal serum: cell ratio in an ab screen
2:1
what does Coombs control cells contain
IgG coated RBC
what is the function of ab potentiators
reagents that speed up the ag-ab rxn
what does albumin do in enhancement media
reduce the zeta potential between RBCs to increase 2nd stage agglutination
how long do samples have to incubate using albumin enhancement media
30 min to 1 hr
what is the ionic strength of LISS
0.3M
is LISS stronger or weaker than normal saline
stronger
what is added to LISS to prevent RBC lysis at low ionic strength
glycine
what does LISS enhance
ab uptake
what is the incubation time for using LISS
10-15 mins
____ volume of serum and LISS is required
equal
if extra serum is added to LISS what happens
decreases test sensitivity
if extra LISS is added to serum what happens
increases nonspecific pos rxn
what potentiating media is water soluble polymer used to increase AB uptake
PEG
how long is the incubation time using PEG
15 mins
do you read at 37C using PEG
no
what kind of abs may not be detected when using PEG
IgM
what kind of inhancement media is positively charged polymer hexadimethrine bromide
polybrene
what kind of inhacement media is rapid and sensitive method for ab ID
polybrene
is the indirect or direct method used with polybrene
direct
how does aggregation of RBC happen using polybrene
cross linking of ab molecules
how is aggregation of RBC dispersed in polybrene
neutral salt solution
what does PEG do to the abs
concentrated the ab in the test environment
once the neg charge is removed on RBC using proteolytic enzymes what happens to the zeta potential
reduces
what kind of immunoglobulins react in the IS phase
pentameric IgM
why is the RT phase used when the IS phase is positive
to allow for more time for the IgM abs to react
what testing phase does monomeric IgG and IgG react
AHG phase
what does it mean if you get a pos auto control
unexpected auto/allo ab or a pos DAT
why will ABO abs not be detected in an Ab screen
because the regents are O cells
what must you look for in an Ab panel to confirm an Ab ID
at least 3 positive and 3 neg cells
def? the lowest conc of ab against a particular ag
ab titer
Antibodies are excluded using RBCs that are homozygous for the corresponding antigen because:
Antibodies may show dosage
A request for 8 units of RBCs was received for patient LF . The patient has a negative antibody screen, but 1 of the 8 units was 3+ incompatible at the AHG phase. Which of the following antibodies may be the cause?
anti-Kp a
The physician has requested 2 units of RBCs for patient DB, who has two antibodies, anti-L and anti-Q. The frequency of antigen L is 45%, and the frequency of antigen Q is 70% in the donor population. Approximately how many units will need to be antigen-typed for L and Q to fill the request?
12
Anti-Sd a has been identified in patient ALF . What substance would neutralize this antibody and allow detection of other alloantibodies?
urine
Patient JM appears to have a warm autoantibody. She was transfused 2 weeks ago. What would be the next step performed to identify any alloantibodies that might be in her serum?
Warm differential adsorption
Which of the following is not involved in the acquired immune response?
Phagocytosis
Which cells are involved in the production of antibodies?
B lymphocytes
Which of the following cells is involved in antigen recoga. nition following phagocytosis?
T lymphs
The role of the macrophage during an antibody response is to:
Process antigen and present it.
Which of the following immunoglobulins is produced in the primary immune response?
IgM
Which of the following immunoglobulins is produced in the secondary immune response?
IgG
Which of the following MHC classes encodes complea. ment components?
Class II
Which of the following immunoglobulins is most efficient at binding complement?
IgM
Which portion of the immunoglobulin molecules con(adaptive) tains complement binding sites?
Heavy chain constant region
Which complement pathway is activated by the forma2. tion of antigen-antibody complexes?
classical
Which of the following is known as the “recognition unit” in the classical complement pathway?
C1q
Which of the following is known as the “membrane attack complex” in the classical complement pathway?
C5b, C6, C7, C8, C9
Which of the following immunoglobulin classes is capable of crossing the placenta and causing hemolytic disease of the newborn?
IgG
Which of the following refers to the effect of an excess amount of antigen present in a test system?
postzone
Which of the following refers to the presence of an excess amount of antibody present in a test system?
Prozone
Which one of the following properties of antibodies is NOT dependent on the structure of the heavy chain constant region?
Affinity for antigen
Molecules that promote the update of bacteria for phagocytosis are:
Opsonins.
Select the term that describes the unique confirmation of the antigen that allows recognition by a corresponding antibody.
Epitope
Which of the following terms refers to the net negative charge surrounding red blood cells?
Zeta potential
