Abbott CELL-DYN 3200 System Operator's Manual page 122

Principles of Operation
Operational Messages and Data Flagging
Cell Populations and Flagging
Fragile WBCs
Lyse-Resistant RBCs
3-28
Typically, fragile WBCs are abnormal lymphocytes that are present in chronic
lymphocytic leukemia (CLL) and are the "smudge cells" that appear when the
blood smear is made.
When processing samples in the Patient mode (Patient is selected as the Specimen
Type in the RUN screen), if fragile WBCs are present the WBC (WOC) count may
be abnormally low due to the gradual destruction of the cytoplasmic membrane of
these fragile cells by the lysing agents during the Run cycle.
When the FWBC flag displays, repeat the specimen using Specimen Type Fragile
WBC. This selection uses the HGB sample dilution containing intact WBC nuclei.
This Nuclear Optical Count (NOC) provides a more accurate WBC count when
fragile WBCs are present.
Resistant RBCs are red blood cells which contain abnormalities or whose
membranes have been altered, making them more resistant to the lysing process.
When running samples in the Patient mode, the hypo-osmotic lysing ability of the
WBC Lyse reagent is usually insufficient to lyse any lyse-resistant RBC cells, if
present, in the time allotted for the WBC count. Consequently, the unlysed RBCs
may be erroneously included in the WBC count, resulting in a falsely elevated
count.
In normal patient samples, lyse-resistant RBCs are either absent or their number is
negligible. In patient samples with a significant number of lyse-resistant RBCs,
usually there is also a significant amount of stroma interference present in the N1
region below the dynamic WOC threshold on the 0º / 10º scatterplot.
When stroma interference is suspected and other conditions are met, the RRBC
(Resistant RBC) flag is displayed, alerting the user to run the specimen in the
Resistant RBC mode (Resistant RBC is selected as the Specimen Type). The WBC
lyse time is extended, allowing for a complete lysing of the lyse-resistant RBCs to
obtain an accurate WBC count.
For samples suspected of containing NRBCs or resistant RBCs, or those whose
smear review indicates the presence of NRBCs (e.g., sickle cells or target cells),
run the sample(s) in Resistant RBC specimen type to verify the WBC count.
Section 3
CELL-DYN 3200 System Operator's Manual
®
9140181K—July 2002