Blood Unit 6
White Blood Cells (Leucocytes)
Objectives
• Introduction
• Leucopoiesis
• Classification
• Morphology
• Properties
• Functions
• Applied physiology
• Recent advances
Introduction
• Why leucocytes called white cells??
• Gabriel Andral,a French professor of medicine and William Addison, an English country practitioner reported simultaneously the first description of leucocytes (1843)
• Play important role in immunity of the body
• These are also called Scavengers & Microscopic policemen
Leucopoiesis
Definition
The process of development and maturation of
white blood cells(leucocytes), is called leucopoiesis.
Normal range of WBC
-At birth,in full term infant: 20,000/cumm of blood
-Infants upto 1 yr of age:6000-16,000/cumm of blood
-Adults:4000-11,000/cumm of blood
TLC < 4000/µL( Leucopenia)
1. Infections by non-pyogenic organisms e.g. typhoid fever
2. Viral infections, influenza,smallpox,mumps etc
3. Protozoal infections
4. Starvation & malnutrition
5. Aplasia of bone marrow
6. Bone marrow depression
Properties Of WBC's
* Diapedesis
* Opsonization
* Chemotaxis
* Phagocytosis
* Degranulation
FUNCTIONS
Neutrophils
* 1st line of defense
* Granules contain enzymes like lysosome
* Antibody like substances -> Defensins
Eosinophils
• Defense (specially against parasites )
• Role in allergic reactions
• Substances present in granules
1. Major basic protein
2. Eosinophilic cationic proteins
3. Eosinophil peroxidase
4. Aryl sulphatase B
Basophils
• Role in allergic responses
• Substances present in granules
1. Histamine
2. Heparin
3. Hyaluronic acid
4. Proteases & Myeloperoxidase
Monocytes
• 1st line of defense
• Motile & phagocytic
• Precursors of tissue macrophages secrete:
1. Interleukin 1
2. Colony stimulating factor
3. Platelet activating factor
Lymphocytes
• Immunity
1.T- Lymphocyte -> Cellular Immunity
2.B- Lymphocyte -> Humoral Immunity
APPLIED PHYSIOLOGY
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