1. Physiological FunctionsOf
White Blood cells
Dr. Ghusoon Ghanem

2. Objectives: WBCs
Identify the different types of WBCs
Enumerate the functions of the various types of WBCs
Describe the steps of formation of WBCs
List the factors required for their maturation.
Infer the importance of total and differential WBC counts
Define the terms leucocytosis and leucopenia
Define leukemia

3. White Blood Cells (WBCs)
Total Leucocyte count (TLC)
,000 /μL
Types of WBCs
Granulocytes contain granules
Neutrophils
Eosinophils
Basophils:
Agranlocytes
Lymphocytes
Monocytes
Differential count: DLC
Neutrophils %
Lymphocytes %
Monocytes %
Eosinophils %
Basophils %

4. The Granulocytes Eosinophils 0-4%; 10-12 µ Basophils 0-1% 8-10 µ
Neutrophils %
10-12 µ in size; 2-5 lobed nucleus; Older the cell more the lobes-
(polymorphonuclear leukocytes);
Small colored granules which contain enzymes, Defensins, oxidants
Action: by Phagocytosis
Life span: a few hrs: 4-8 hrs in blood; 4-5 days in tissues
Fast response; neutrophilia in bacterial diseases; neutropenia in drug toxicity
Eosinophils 0-4%; µ
Bi-lobed nucleus; coarse acidophilic granules
Phagocytose antigen-antibody complexes; destroy parasites
Granules contain various enzymes : MBP
Increase in allergic conditions; decrease during stress-corticoids
Basophils 0-1% µ
Nucleus usually bi-lobed;
large deep purple colored granules which often cover the nucleus
Secrete heparin, serotonin, histamine: help in inflammation

5. Agranular WBCs
Monocyte µ;3-8%; circulate in blood for about hrs.
long life span (many weeks to months) after change into macrophages in
tissues
Single kidney shaped nucleus
Phagocytosis after converting in to macrophages
Lymphocyte µ (small); µ (large); 20-25%; mostly formed in
lymhoid tissue; some in bone marrow.
Nucleus surrounded by thin ring of cytoplasm; long life span inside tissues,
but only a few hours in blood
B and T lymphocytes: Immune mechanisms
B lymphos form plasma cells
Natural Killer (NK) cells against viruses, cancer

6. Physiology and Functions of WBCs
Life span: few hours to a few days
They have Major Histocompatibility Antigens on surface:
-Identification of the “SELF”
Main functions:
combat infection by phagocytosis
immune mechanisms
Adhesion molecules
Selectins: on endothelial cells - attach to CHOn on neutrophil surface
Integrins on neutrophils: also make
WBCs stick to endothelial surface, &
help them to move out of the blood vessels
When required , they escape from the blood via capillary pores (emigration) helped by integrins
enter tissue and have their action there by phagocytosis

7. 1 . Chemotaxis : attraction of WBCs to site of infection Promoted by
Phagocytosis
Mainly by neutrophils and monocytes
Steps of Phagocytosis
1 . Chemotaxis : attraction of WBCs to site of infection
Promoted by
i. bacterial toxins
ii. kinins from damaged tissues
iii. CSFs
2. Adherence
phagocyte attaches to microbe using proteins
3. Ingestion
pseudopods from WBC surrounds microbe
formation of a PHAGOSOME

8. 5. Killing as result of the above. Residual bodies get left behind
4. Digestion
Phagosome enters cytoplasm of WBC and merges with LYSOSOME: Phago-lysosome: secretion of lysozomal enzymes followed by release of oxidants: oxidative burst
5. Killing as result of the above. Residual bodies get left behind 1
Microbe
CHEMOTAXIS
Lysosome
Digestive
enzymes
Pseudopod
Phagocyte
ADHERENCE
INGESTION
Plasma
membrane
DIGESTION
KILLING
Residual body
(indigestible
material)
Digested microbe
in phagolysosome 2 3 4 5
Phases of phagocytosis

9. Formation of WBCs: Hemopoiesis

10. Pluripotent stem cell Lymphoid stem cell Myeloid stem cells
Colony Forming Unit
G/M T
lymphocyte
T lymphoblast
Neutrophil
monocyte
Eosinophilic
myeloblast B
lymphocyte
B lymphoblast
eosinophil NK
Cell
NK lymphoblast
Basophilic
myeloblast
basophil
Granulocytes and monocytes : formed only in the BONE MARROW stored in the bone marrow, and
released into circulation. Lympocytes and Plasma cells also in lymhoid tissue, are stored in lymhoid
tissue . Few released into circulation
Various Colony Stimulating factors (CSFs or Growth Inducers) help in their formation:
IL1, IL6 and IL3 (multi CSF)
These are proteins in nature

11. Disorders of white blood cells
The number of leukocytes, or white blood cells, in the peripheral circulation normally ranges from 4000 to 10,000/μL of blood.
The term leukopenia describes an absolute decrease in white blood cell numbers. The disorder may affect any of the specific types of white blood cells:
Neutropenia
Lymphopenia
The term leukocytosis describes an absolute increase in in white blood cell numbers and also may affect any of the specific types of white blood cells:
Neutrophilia
Eosiniphilia
Basophilia
Lymphocitosis
Monocitosis

12. Normal WBC count: 4000-11000 Leuocytosis >11000 Leuopenia < 4000
Neutophils
Infections, Burns, inflammation
Lymphocytes
Viral infections
Monocyts
Viral, fungal infections, TB,
Chronic disease
Eosinophils
Some viral infections
Bacterial infections (typhoid)
Bone marrow suppression
Drugs: antibiotics
corticosteroids

13. Leukemias (blood cancer)
Typical eg:
8 year child; high fever;
pain throat; difficulty in swallowing
swollen septic tonsils
TLC 18,500
DLC: N. 88%; L 10%; E 2%
Elderly person; exposure to radiation
Hex of intractable fever and infections;
Loss of appetite
TLC 2000
DLC: N. 30% L 60%; E 4% ;
6% other WBCs
Leukemias
(blood cancer)

14. Summary
1. TLC, types of WBC, DLC
2. Description of various types of WBCs and their actions
3. Phagocytosis
4. Development of WBCs and factors associated
5. Define leucocytosis/leucopenia with typical examples
6. Leukemias or blood cancer