Page 654 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

638 PART 8 ■ Fundamentals of Hematological Analysis
More recently, monoclonal antibodies directed against
CD20, CD25, CD33, CD45, and CD52 have been developed.
Be ore treatment, f ow-cell analysis is critical or con rming
that the antigen is expressed by the o ending cells. During
and a er treatment, f ow cytometry is used to veri y bind-
ing o the antibody and to monitor the e cacy o tumor cell
eradication.
Paroxysm al Nocturnal Hem oglobinem ia Testing
T e detection o paroxysmal nocturnal hemoglobinemia
(PNH) by the traditional methods o Ham’s (acid hemolysis)
and the sucrose lysis test has been replaced in many clinical
laboratories by f ow cytometry analysis. T e glycosylphos-
phatidylinositol (GPI)-linked proteins, CD55 and CD59, are
examined to determine i a de ciency or absence o these cell
sur ace markers exists. I a de ciency or absence o CD55
and CD59 is established, the condition is diagnostic o PNH.
Fetal Hem oglobin
Detection o etal hemoglobin and F cells by f ow cytometry
is becoming common. T e assay uses monoclonal antibod-
ies to hemoglobin F. T is analysis allows or the detection o
a variety o diseases including sickle cell disease and etal-
maternal hemorrhage. In addition, this methodology allows
or quantitation o etal hemoglobin.
Blood Parasites
Malarial parasites can be screened by f ow cytometry meth-
ods. I erythrocytes are stained with acridine orange, the
mature erythrocytes containing no DNA do not f uoresce
with this stain. However, malarial erythrocytes contain DNA
and thus will f uoresce.
Cell Functioning Analysis
Every event that occurs during the process o lymphocyte
activation can be measured by f ow cytometry. T e measure-
ments with the greatest clinical signi cance include tyrosine
phosphorylation, calcium f ux, oxidative metabolism, neo-
antigen expression, and cellular proli eration.
Flow cytometry measurement o the oxidative burst in
neutrophils has been used as a screening test or chronic
granulomatous disease (CGD).
Chrom osom al Analysis
Flow cytometry can be used or karyotyping analysis. A
chromosomal histogram consists o seven peaks that repre-
sent the di erent groups o chromosomes. By evaluating the
peaks, various disorders can be diagnosed.
Cell Sorting
Some f ow cytometers have additional hardware that allows
them to act as cell sorters. A er quickly making the appropri-
ate measurements, the computer makes the decision to sort
or isolate a single cell by applying a charge to that cell just as
it leaves the f ow cell. T e cell is electrostatically def ected
into a test tube. Any cell type can be sterilely sorted and
recovered alive based on any combination o light scatter and
f uorescence measurements. T e cell type o interest can be
separated rom a complex mixture o cell types even though
it may be an extremely rare or minor subpopulation.
DIGITAL MICROSCOPY
Recent advances in arti cial neural networks (ANNs), image
analysis, and slide handling have combined to produce
instruments that automate manual di erentials in new ways.
T is new technology, re erred to as automated digital cell
morphology (Fig. 30.23), provides an unprecedented level o
e ciency and consistency. In its simplest orm, automated
digital cell morphology is a process where blood cells are
automatically located and preclassi ed into categories o
blood cells. Images o these cells are retained or con rma-
tion by a technologist and can be shared electronically and
stored as digital images. T is adaptability allows or uture
review and comparisons by laboratory pro essionals and
physicians.
Arti cial Neural Networks
An ANN is an in ormation-processing model that simulates
the way the human brain processes in ormation. ANN emu-
lates the neural structure o the brain, which is composed o
a large number o highly interconnected processing elements
(neurons) working together to solve speci c problems.
ANNs have been around since the 1940s, but it was not until
the mid-1980s that algorithms became sophisticated enough
and computers power ul enough or general applications to
develop.
Digital Cell Morphology
New hardware and the development o databases have aided
in developing image analysis systems that can nally meet
the demands o the hematology laboratory. T e most dra-
matic change in microscopy over the last three decades is
the ability to digitize image specimens and transmit these
images electronically or remote analysis. T is capability is
now called virtual microscopy.
FIGURE 30.23 CellaVision DM-1200. (Courtesy o Cellavision,
Inc.)