The prevalence of this false-negative reaction
does vary depending on reagent strip brand, with some brands showing greater sensitivity than others.
Failure to add the anti-D reagent, heavy cell suspension, presence of contaminants in the sample, or under-centrifugation/incorrect calibration during testing can result in false-negative reactions
. Sample mix-ups and/or clerical errors also can lead to incorrect determination or interpretation of results.
It is unlikely that those tumors that did not stain for CK20 can be attributed to false-negative reactions
from tissue processing, because diffuse CK7 immunoreactivity was present in all the cases.
These have the benefit of controlling for false-negative reactions
at each well position.
The FD705 antibody reacts equally with all seven B27 variants and thus no false-negative reactions
are to be expected .
Timing errors may produce false-positive or false-negative reactions
. False positives may also occur if other proteins are present in the urine.