Siemens ADVIA 2120, Operator'S Manual, Page: 294 / 477

Methods 8-25
Peroxidase Method
Cytochemical Reactions
The peroxidase cytochemical reactions consist of three steps:
Step 1
Red blood cells are lysed using ADVIA 2120/2120i PEROX 1 reagent
and the high temperature in the reaction chamber.
Step 2
White blood cells are fixed using ADVIA 2120/2120i PEROX 1 reagent.
Step 3
White blood cells are stained using ADVIA 2120/2120i PEROX 2
reagent and ADVIA 2120/2120i PEROX 3 reagent.
White blood cells are identified based on size and different intensity of
peroxidase reaction (staining).
Neutrophils, eosinophils, and monocytes are stained based on their levels of
peroxidase activity. Since lymphocytes, basophils, and large unstained cells
contain no peroxidase, these cell types remain unstained.
Perox Temperature Control
Temperature control is critical to lysing the red blood cells. The perox reaction
chamber temperature, which is automatically monitored by the analyzer, must be
between 58°C and 72.1°C.
If you want to check the perox reaction chamber temperature, use the Analyzer
Status tab.
If you need to adjust the perox reaction chamber temperature:
1. At the Special Procedures menu, select
Adjust Lamp / Temp
.
2. Select
Perox Temperature
.
ADVIA 2120/2120i PEROX 1
NOTE:
For more detailed information on the contents of ADVIA 2120/2120i
PEROX 1 reagent, please see Chapter 8.
ADVIA 2120/2120i PEROX 1 is the first reagent added to whole blood sample
in the heated peroxidase reaction chamber. Its function is to lyse the red blood
cells and fix the white blood cells.
Surfactants (sodium dodecyl sulfate and Brij-35) in combination with thermal
stress lyse the red blood cells.
Formaldehyde fixes the white blood cells. The hypertonic environment causes
some shrinkage and crenation of the white cells. This increases the refractive
index of the cells and enhances the detection of lymphocytes over noise.