The White blood cell (WBC) count
Dr. Haneen Abdelsalam Ali
WBCs (Leukocytes) are round shaped, nucleated
cells. They are found throughout the body including
the blood and lymphatic system.
• The normal level of WBCs under basal condition
of complete physical and mental rest is 4500-11000
cell/ mm3. A condition with WBCs level more than
11000 mm3 is called leukocytosis. The opposite
condition, leukopenia, is an abnormally low WBCs
count.
• WBCs make up approximately 1% of the blood
volume in a healthy adult.
• The lifespan of WBCs varies from few days to few
weeks.
• Acting together, WBCs provide our body with
powerful defenses against tumor and viral,
fungal, bacterial, and parasitic infections
• The name "White Blood Cell" derives from the
fact that after centrifugation of a blood sample,
the WBCs are found in the Buffy coat, a thin layer
of nucleated cells between the sedimented RBCs
and the blood plasma, which is typically white in
color. The scientific term leukocyte directly
reflects this description, derived from Greek
leuko - white, and cyte - cell.
• Leucopoiesis is the process of WBCs/leucocytes
production.
Aims of WBC Count Experiment
• WBCs count is part of the complete blood
count (CBC) test that is used to evaluate the
overall health and detect a wide range of
disorders such as anemia, infection and
leukemia
• To know whether or not subjects/patients are
suffering from Leukocytosis (the increase in
the no. of WBCs to more than 11000/mm3) or
Leucopenia (the decrease in the no. of WBCs
to less than 4000 or 1500 /mm3)
• To learn how to use the manual method in the
lab to get the number of white blood cells.
• White blood cell count is the total number of
leukocytes in a volume of blood, expressed as
thousands/μl
• Methods
1. Manual method
2. Electronic cell counter
• Manual differential white cell count material
and instruments
1. Anticoagulated whole blood (using EDTA or
heparin as an anticoagulant) or capillary
blood can be used.
2. Turk’s solution (diluting fluid) composed of:
•Glacial acetic acid 2.00 ml
• Gentian Violet (1% w/v) 1.00 gm
• Distilled water 97.00 m
3. pipette
4. Haemocytometer / “Neubauer” chamber is
the counting chamber with a coverslip.
5. Microscope
6. Lancet, Alcohol 70%, and Cotton
• Procedure:
• Obtain a drop of blood in the same manner as in RBC
count.
• Remove blood from outside of the pipette with a clean
gauze.
• Aspirate diluting fluid, The dilution is 1:20.
• Gently rotate the pipette horizontally with your hand
to ensure a proper amount of mixing for 3 minutes.
• After mixing discard the first four drops of the mixture.
• Fill the counting chamber with diluted blood(10 um)by
holding the pipette at 45o with the
• slide and allow the mixture to seep under the cover
slip, the filled chamber should
• be allowed to stand for a minute prior to counting.
• Count the WBCs using the low power 10 x objectives.
• Calculation:
• Count the number (N) of cells in 4 large squares located at
the four corners of the
• chamber. The size 4 large squares in which “N” numbers of
cells are found is:
• 1 x 1 x 1/10 x 4 = 4/10 mm3
• Where 1 mm is the sideline of the large square, 1/10 mm is
the depth of the counting
• chamber between coverslip and the ruling, 4 is the number
of large squares used to count.
• Therefore the total numbers of cells in 1 mm3
• are = N x 10/4 (diluted sample).
• The actual total number of cells before dilution should be:
• N x 10/4 x 20 = N x 50
Some Medical Consideration: Leukocytosis
• A total WBCs count above 11.000 cells/mm3 is
referred to as leukocytosis.
• Leukocytosis generally indicates that a:
• Bacterial infection such as appendicitis,
tonsillitis, ulcers and urinary tract infection
• Hemolytic disease of newborn
• Leukemia
• Pregnancy
• Cigarette smoking
Some Medical Consideration: Leukopenia
• Leukopenia is a condition characterized by a
decreased number of white cells in the blood,
which is usually due to:
• Some bacterial infections such as typhoid fever,
brucellosis, and typhus fever
• Rheumatoid arthritis
• Viral disease such as measles and infectious
hepatitis
• Systemic Lupus Erythematosis
• Certain drugs such as such as corticosteroids,
radio therapy and chemotherapy.
leukemia
• In leukemia, this rapid, out of-control growth
of abnormal cells takes place in the
• Leukemia is a cancer of the blood and bone
marrow. In simple terms, cancer is defined as
the uncontrolled growth of abnormal cells.