TOPIC 3 - P3 Flashcards
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Improper specimen (refrigerated, clotted) may cause in vitro complement attachment.
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ overcentrifugation and overreading
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ centrifugation after the incubation phase when PEG or other positively polymers are used as an enhancement medium
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Bacterial contamination of cells or saline used in washing
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Dirty glassware
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Presence of fibrin in the test tube may mimic agglutination
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Cells with a positive DAT will yield a positive IAT
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Polyagglutinable cells
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Saline contaminated by heavy metals or colloidal silica
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ using a serum sample for a DAT (use EDTA, ACD or CPD anticoagulated blood)
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Samples collected in gel separator tubes may have unauthentic complement attachment
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Complement attachment when specimens are collected from infusion lines infusing dextrose solutions.
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Preservative-dependent antibody directed against reagents
False-positive
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Inadequate or improper washing of cells
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Failure to wash additional times when increased serum volumes are used
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Contamination of AHG by extraneous protein (i.e., glove, wrong dropper)
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ High concentration of IgG paraproteins in test serum
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Early dissociation of bound IgG from RBCs due to interruption in testing
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Early dissociation of bound IgG from RBCs due to improper testing temperature (i.e, saline or AHG too cold or hot)
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ AHG reagent nonreactive because of deterioration or neutralization (improper reagent storage)
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Excessive heat or repeated freezing and thawing of test serum
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Serum nonreactive because of deterioration of complement
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ AHG reagent, test serum, or enhancement medium not added
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Under-centrifuged or over-centrifuged
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Cell suspension either too weak or too heavy
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Serum: cell ratios are not ideal
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Rare antibodies are present that are only detectable with polyspecific AHG and when active complement is present.
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Low PH of saline
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Inadequate incubation conditions in the IAT
False-negative
(SOURCES OF ERROR IN ANTIHUMAN GLOBULIN TESTING)
DETERMINE IF FALSE-POSITIVE OR FALSE-NEGATIVE…
✓ Poor reading technique
False-negative
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
_________ reported on the adaptation of the automated low ionic polybrene (LIP) technique
1980: Lalezari and Jiang
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
relies on _________ to rapidly sensitize cells with antibody
low ionic conditions
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
_______ potent rouleaux-forming reagent
Polybrene:
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
Polybrene is added to allow the sensitized cells to approach each other and permit cross-linking by the attached antibody. Then a _________ is then added to reverse the rouleaux
high ionic strength solution
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
+ reaction: ________
presence of agglutination
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
If performed,__________ reagent must be used
monospecific anti-IgG
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
___________ used microplates for a number of different grouping procedures (includes IAT)
Crawford and colleagues
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
________ adapted the LIP technique for use in microplates
Redman and associates
(Modified and Automated Antiglobulin
Test Techniques)
- Low Ionic Polybrene Technique
________ antibody is missed
anti-Kidd
(Modified and Automated Antiglobulin
Test Techniques)
- Enzyme-linked antiglobulin test (ELAT)
procedure:
1. _________ is added to a microtiter well and washed with saline
2. _____, which has been labeled with an enzyme, is added
3. _______ will bind to IgG-sensitized RBCs
4. Excess antibody is removed, and _______ is added.
5. Amount of color produced is measured _______
- optical density is usually measured at _____
- RBC suspension
- AHG
- Enzyme-labeled AHG
- enzyme substrate
- spectrophotometrically ; 405 nm
(Modified and Automated Antiglobulin
Test Techniques)
- Solid Phase Technology
uses either ______ or_________
test tubes or microplates
(Modified and Automated Antiglobulin
Test Techniques)
- Solid Phase Technology
DAT: antibody is attached to a ________, and RBCs are added.
microplate well
(Modified and Automated Antiglobulin
Test Techniques)
- Solid Phase Technology
_______ If antibody is specific for antigen on RBCs, the bottom of the well will be covered with suspension
[(+) rxn]
(Modified and Automated Antiglobulin
Test Techniques)
- Solid Phase Technology
if no such specificity occurs, RBCs will settle to the bottom of the well ______
[(-) rxn]
(Modified and Automated Antiglobulin
Test Techniques)
- Solid Phase Technology
IAT: known RBCs are bound to a well that has been treated with _______ or _____. Test serum is added to RBC-coated wells, and if antibody in serum is specific for antigen on fixed RBCs, a positive reaction occurs (same with (+) rxn above)
glutaraldehyde or poly L-lysine
(Modified and Automated Antiglobulin
Test Techniques)
- Gel Test
process that detects RBC antigen-antibody reactions by means of using a chamber filled with ___________
gel acts as a trap; free unagglutinated RBCs form pellets in the bottom of the tube [_____], whereas agglutinated RBCs are trapped in the tube for hours [_______]
polyacrylamide gel ; (-) rxn ; (+) rxn
(Modified and Automated Antiglobulin
Test Techniques)
- Gel Test
________: does not contain any specific reagent and acts only by its property of trapping agglutinates
main applications: _______ and identification with _______ or _____and _________
Neutral gel ; antibody screening ; enzyme-treated or untreated RBCs ; reverse ABO typing
(Modified and Automated Antiglobulin
Test Techniques)
- Gel Test
________ use a specific reagent incorporated into the gel
useful for _________
Specific gel tests ; antigen determination
(Modified and Automated Antiglobulin
Test Techniques)
- Gel Test
__________: AHG reagent is incorporated into the gel.
Ex. in an IAT gel, ____ of a 0.8% RBC suspension is pipetted onto a gel containing AHG, serum is added, and the tube is ______ after a period of incubation
C. Gel low ionic antiglobulin test (GLIAT)
- 50 μL ; centrifuged
(Modified and Automated Antiglobulin
Test Techniques)
- Gel Test
C. GLIAT
- For the DAT, 50 μL of a 0.8% RBC suspension in ______ (ID-Diluent 2) is added to the top of each microtube of the LISS/Coombs ID cards. The cards are centrifuged at ________ for ____
LISS solution ; 910 rpm for 10 minutes.