COULTER HmX Hematology Analyzer, Reference Manual

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PN 4237523A 1-5
USE AND FUNCTION
METHOD HISTORY
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Differential Measurement
The COULTER VCS established WBC differential technology using three measurements:
individual cell volume, high-frequency conductivity, and laser-light scatter.
The combination of low-frequency current, high-frequency current, and light-scattering
technology provides abundant cell-by-cell information that is translated by the instrument
into conventional stained film leukocyte categories. Correlation between the frequency of the
different cell types using stained film microscopy and this system is greater than 0.9 for
lymphocytes and granulocytes, and 0.7 for mononuclear cells.
Volume Analysis
Electronic leukocyte volume analysis, using low-frequency current, has been used since
1967.
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It has been evaluated as a possible adjunct to the differential white cell
count.
19, 20, 21, 22
Conductivity Analysis
Cell walls act as conductors to high-frequency current. As the current passes through the cell
walls and through each cell interior, it detects differences in the insulating properties of cell
components. The current characterizes the nuclear and granular constituents and the
chemical composition of the cell interior.
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Light Scatter Analysis
Beckman Coulter's experience in flow cytometry dates back decades to Fulwyler's pioneering
use of light scatter for cell analysis.
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Loken et al. and Jovin et al. discuss the relationship of
particle size and refractivity to the angle of light scattered from a laser beam.
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Reticulocyte (Retic) Analysis
Reticulocytes are immature, nonnucleated erythrocytes retaining a small network of
basophilic organelles, comprised of RNA and protoporphyrin. The enumeration of
reticulocytes provides a simple, effective means to determine red cell production and
regeneration.
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The most common means of measuring reticulocytes is to use supravital dyes, such as New
Methylene Blue or Brilliant Cresyl Blue. These dyes precipitate and aggregate the basophilic
substances within the reticulocyte, resulting in a granular, staining pattern easily seen with
light microscopy.
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%
Analysis
Dennis B. Dorsey, MD, proposed in 1963 that the relatively constant blood cell indices could
be used to follow the performance of hematology instrumentation.
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Brian Bull, MD,
improved the technique and named it
%
Analysis.
34
%
Analysis uses a "weighted moving average" of patient sample results because Koepke said
that QC materials "ideally should be similar in structure and in reactivity to the patient
constituent being measured, [and] therefore freshly drawn patient blood samples seem to be
the most appropriate [QC material]."
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Bull explains, "The analyser [sic] is considered to be
‘in control’ when the MCV, MCH, and MCHC determined on a batch of 20 patients by use of
the
%
algorithm are within 3% of the expected mean indices of the population."
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