2. Assessment of Circulating WBC
White blood cells (WBCs), also called leukocytes, are cells that circulate in the blood and
the lymphatic system that help protect the body against infections. They are an important
part of the body's immune system and also have a role in inflammation, allergic responses,
and protection against cancer. We have five types of white blood cells: neutrophils,
lymphocytes, monocytes, eosinophils, & basophils.
First: White Blood Cell (WBC) Count
Also Known As WBC Count, Leukocyte Count, and White Count. The white blood cell
(WBC) count measures the totals number of white blood cells in a blood samples.
3. 3
Purpose: 1-To diagnose of conditions that can affect the number of white blood cells (WBCs),
such as an infection, inflammation or a disease 2-to monitor treatment of a disorder or to monitor
therapy that is known to affect WBCs.
Objectives
To calculate the number of WBC cells/μL in blood sample.
Procedure
Put the cover slip or glass slip on the top of grid area in the hemocytometer Chamber (use air
tight technique).
Dilute the blood sample to 1: 20 with WBC diluting fluid (Turk s solution) which contains
glacial acetic acid (To lyses the RBC and platelets and to fix WBCs) and violet solution (to
stain WBCs).
Load the sample into the laoding area in the chamber.
Count the cells in the 4 large squares for WBC.
4. WBC count
The hemocytometer contains 2 Neubauer counting chamber.
Each chamber contains:*4 WBC counting squares *Each contains 16 squares. Count
only the cells that on those lines (ex: L-shape).
Counting Grid Area
5. Calculation
Count the cells in the four large corners square of the Neubauer chamber.
Dilution factor= reciprocal of dilution = (20)
The area counted is 4 mm2 and the depth is 0.1 mm; therefore the volume factor is 0.4 mm3.
**Now calculate the average of both top and bottom counting chamber reading
•Total WBC/mm3 or / microliter =
Total no. of WBC in top counting chamber + Total no. of WBC in bottom counting chamber
2
6. These are the normal ranges of WBCs per microliter of blood (mcL):
Critical value =
<2500 or >30,000 / microliter.
Understanding the results of a WBC count
Abnormal test results are classified by numbers that are higher or lower than the normal range for age.
Leukopenia: is the medical term used to describe a low WBC count. A low number can be
triggered by:
HIV Autoimmune disorders. Lymphoma.
Bone marrow disorders
or damage.
Severe infections. Liver and spleen
diseases.
Lupus. Radiation therapy. Some medications, such
as antibiotics.
7. Leukocytosis: is the medical term used to describe a high WBC count. This can
be triggered by:
Smoking. Tissue damage. Leukemia.
Infections such as
tuberculosis.
Tumors in the bone
marrow.
Pregnancy.
Inflammations stress & exercise Some medications,
such as
corticosteroids.
Allergies. Asthma.
8. WBC differential determines the percentage of each type of white blood cell present in
the blood sample. A differential can also detect immature white blood cells and
abnormalities, both of which are signs of potential issues.
Procedure:
Blood Smear Preparation:
1. Prepare thin films of blood by Place a drop of blood in the central line of a slide about 1-2 cm from
one end.
2. The spreader is placed at an angle of 45 degrees to the slide and then moved back to make contact
with the drop.
3. The drop should spread out quickly along the line of contact of the spreader with the slide.
4. The moment this occurs the film should be spread by a rapid, smooth, forward movement of the
spreader.
5. Label slide in pencil with patient's full name and date. Allow slides to air dry.
Second: Differential Leukocyte Count
9. Staining:
1. Cover the slide with stain (Wright or May-Grunewald-Giemsa stain) for 1-2 minutes
taking care that it does not dry on the slide.
2. Now dilute this with equal amount of buffer water.
3. Diluted stain is allowed to act for 3-5 minutes and then flooded off with buffer (or top
water).
4. Discard excess buffer away and dry in the air.
10. The count
The dry and stained film is examined without a cover slip under oil immersion objective. For
differential leukocyte counts:
• Choose an area where the morphology of the cells is clearly visible.
• Do differential count by moving the slide in area including the central and peripheral of the
smear.
11. • A total of 100 cells should be counted in which every white cell seen
must be recorded in a table under the following heading Neutrophil,
Eosinophil, Basophil, Monocyte and Lymphocyte. Then find the
percentage of each type.
By absolute number of each WBC type
(CORRECT) (% of each cell type x total WBC number)
