Blood Physiology1432

Lecture 3

Leucocytes 1

Professor A M Abdel GaderMD, PhD, FRCP (Lond., Edin), FRSH (London)

Professor of Physiology, College of Medicine &the Blood Bank, King Khalid University Hospital

King Saud UniversityRiyadh

LeucocytesWhite Blood Cells

(WBCs)

Objectives of Lecture -3At the end of this lecture the student should be able to:1.Describe the different types of WBCs2.Recognize the general functions of WBCs3.Describe the genesis and site of formation of WBCs4.Describe the stages of neutrophil formation5.Describe the role of the neutrophil in defending the body against infections6.Describe the process of phagocytosis

Leucocytes (WBCs)Contents

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis– Structure and function of Eosinophils and

basophils

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis– Structure and function of Eosinophils and

basophils

Leucocytes (WBCs)Contents

Blood Film

Hematopoiesis

Formed Elements of Blood• Red blood cells ( erythrocytes )• White blood cells ( leukocytes )

– granular leukocytes• neutrophils• eosinophils• basophils

– agranular leukocytes• lymphocytes = T cells, B cells, and natural killer

cells• monocytes

• Platelets

Leucocytes (WBCs) – cont.

General Characteristics & types of WBCs

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil 0.4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Leucocytes (WBCs) – cont.

General Characteristics & types of WBCs

• Types of WBC2. Agranular WBC

– Monocytes 5.3%• 15-20um, kidney shape nucleus

– Lymphocyte 30%• round nucleus

– small (5-8um) – large (9-15um)

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Leucocytes (WBCs)-cont.

Contents

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Leucocytes (WBCs)-cont.

Contents

Leucocytes (WBCs) – cont.

Genesis (Production) of WBCs

Pluripotential stem cell

Committed Stem cell

RBCs WBCs Platelets

Mylocytic Lymphocytic Linage Linage

Figure 16-5c: Bone marrow

Hematopoiesis

21

Leucocytes (WBCs) – cont.

Genesis (Production) of WBCs- leucopoiesis)

Sites of WBC formation• Granulocytes (neutrophil, basophil,

eosinophil):

– bone marrow

• Agranulocytes – lymphocytes- bone marrow,

thymus, lymphoid tissues– monocytes- bone marrow

23

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Leucocytes (WBCs)-cont.

Contents

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Leucocytes (WBCs)-cont.

Contents

Life Span of WBCs

Granulocytes:• 4 to 8 hrs (transit time ) in blood circulation• 4 to 5 hrs in tissues

– In infections life span a few hours

Monocytes :– 10 to 20 hrs in blood circulation– Leave capillaries to tissues, increase in size

to become tissue macrphages which live for months

Life Span of WBCs-cont.

Lymphocytes:

• A few hrs in blood circulation >> tissues >> lymph >>> Blood (Recirculation)

?Life span: weeks to months

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Leucocytes (WBCs)-cont.

Contents

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils (& macrophages)

– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Leucocytes (WBCs)-cont.

Contents

Leucocytes (WBCs)

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Defense properties of neutrophils (& macrophages)

• Attack and destroy bacteria, viruses

• Sequence of events:– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Netrophils function-cont.

Defense properties of neutrophils & macrophages-cont

Phyagocytosis: Engulfing and killing of bacteria or any

invading organism

Steps: Chemotaxis:

– Bacterial & viral toxins• Products of damaged tissues:

attract neutrophil to accumulate at infected site.

– Opsonization: plasma substances (IgG) attached to the bacteria to make them easy to phagocyte

Diapedesis

Diapedesis

http://www.whfreeman.com/immunology/CH01/diapedesis.htm

Defense properties of neutrophils & macrophages

• Attack and destroy bacteria, viruses

• Sequence of events:– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Defense properties of neutrophils & macrophages

• Attack and destroy bacteria, viruses

• Sequence of events:– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Phagocytosis- cont.

Phagocytosis is selective:Distinguish self from non-self…... How?

– Normal tissues have smooth surface– Normal tissues have protective

protein surface– Antibodies coating bacteria

(Opsonization)

Phagocytosis

Microbial killing

41

Phagocytosis by neutrophils- cont.

Neutrophils attach to bacteria & encircled it with pseudopodia and take it into a vacuole (phagosome).

• One Neutrophil can engulf 3 to 20 bacteria• One Macrophage can engulf up to 100 bacteria

Microbial killing: fusion of neutrophil granules with vacuole,

– Discharge of lysozyme, myeloperoxidase enzymes into the vacuole, killing and digesting the engulfed bacteria.

– Release of Free radicals by oxidizing agents: superoxide, hydrogen peroxide to kill the bacteria

Leucocytes (WBCs) – cont.

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Blood Film

Eosinophils

Function: • Phagocytosis: Phagocytosis is same as neutrophil,

but less efficient

• Chemotaxis: eosinophil attracted towards chronic inflammation/allergic tissue (allergic disease of skin & lungs)

By eosinophil chemotactic factor

Phagocytose (& detoxify) antigen/antibody complexes

Eosinophils cont,

•High eosinophil count:– Parasitic (hook worm, ascaris,

bilharzia)– Allergic (asthma, rhinitis, drug

reaction)– Allergic skin diseases

Leucocytes (WBCs) – cont.

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Leucocytes (WBCs) – cont.

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Blood Film

Basophils

• Similar to tissue mast cells• Non-phagocytic cells• Granules: dark blue color.• Granules contain:

– Heparin– Histamine – Serotonin (5HT).

Released during allergic reactions

Objectives of Lecture -3At the end of this lecture the student should be able to:1.Describe the different types of WBCs2.Recognize the general functions of WBCs3.Describe the genesis and site of formation of WBCs4.Describe the stages of neutrophil formation5.Describe the role of the neutrophil in defending the body against infections6.Describe the process of phagocytosis

THANK YOU

جزيل لكمالشكر