Introduction: - WBC or leukocytes are the colorless and nucleated formed elements of blood. Leukocytes play important role in defense mechanism of the body and protect the body from infection. These cells work like as soldiers.
Classification: -on the base of presence or absence of granules in the cytoplasm, the WBC are classified into 2 types.
1. Granulocytes: - (a) neutrophils (b) eosinophils (c) basophiles.
2. A granulocytes: - (a) monocytes (b) lymphocytes
Total WBC count: - 4000 – 11000/ CU.mm of blood.
Differential WBC count: - life-span
Neutrophils 50-70% 2-5 days
Eosinophil 2-4% 7-12 days
Basophiles 0-1% 12-15 days
Monocytes 2-6% 2-5 days
Lymphocytes 20-30% ½-1 days
Variations in WBC count;-
Increase leukocyte count is known as leukocytosis.
Decrease leukocyte count is known as leucopenia.
Physiological variations:-
1. Age– WBC count high in infant and child and low in adults.
2. Sex – slightly more in males than in females.
3. Time– minimum in early morning and maximum in the afternoon (because increase demand of oxygen in afternoon).
4. Exercise- increase WBC count during exercise.
5. Sleep – WBC count decrease during sleeping.
6. Emotional Condition– like anxiety, stress increase WBC count.
7. Pregnancy– increase WBC count.
8. Menstruation – WBC count increase during menstruation (because during menstruation chance of infection increase).
Pathological variations:-
Leukocytosis: - increase total leukocyte count is called leukocytosis. It occurs in conditions such as:-
1. Infections.
2. Allergy
Most: - highest percentage of WBC in blood is neutrophils (50-70%)
Lowest percentage of WBC in blood is basophiles (0-1%)
Highest life span of WBC is – basophiles (12-15 days)
Lowest life span of WBC is – lymphocyte (½-1 days)
Properties of WBC:-
1. Diapedesis
2. Ameboid Movements
3. Chemotaxis
4. Phagocytosis
Functions of WBC:-
1. Neutrophils with monocytes bothprovides first line defense in the body against the microorganism.
2. Eosinophils :- eosinophils count increase during allergic reaction and parasites infection. Like – malaria, filariasis, allergic reaction, asthma.
3. Basophiles: -basophiles play important role in healing process. So their number increases during healing process.
4. monocytes :- this provide first line defense with the neutrophils. This is largest cell in the all leukocytes. Diameter of this is 14-18 μ.
5. Lymphocytes: - lymphocytes play main role in immunity. Lymphocytes are classified into 3 types:-
(a) T- Lymphocytes which responsible for cellular immunity.
(b) B- Lymphocytes which responsible for the humoral immunity.
(c ) Natural killer cell – lysis of tumor cell.
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