Download HERE - WordPress.com

White Blood cells
Most dreaded enemies…….always exposed
Multiple defense mechanisms
White blood cells/leukocytes
Mobile units of body’s protective system.
Colourless due to lack of haemoglobin so K/a White blood cells
Normal count : 4000-11000/cumm of blood (cumm = 1μl)
Scavengers………..seek out and destroy foreign invader

Five Types

Classified according to the presence or absence of
granules and the staining characteristics of their
cytoplasm.

Leucocytes appear brightly colored in stained
preparations, they have a nuclei and are generally
larger in size than RBC’s.
WBC’s
Presence of granules
Granulocytes
Neutrophils
50-70%
Eosinophils
1-4%
Basophils
0-1%
Absence of granules
Agranulocyte
Monocytes
2-8%
Lymphocytes 20-40%
Differential leucocyte count : Count expressed in terms of
percentage of different types of WBC
Neutrophils










10-14μm
Stain light purple with neutral dyes
Granules are small and numerous—fine
appearance
Several lobes in nucleus (lobes increase with the
age of neutrophil)
65% of WBC count
Highly mobile/very active
Diapedesis—Can leave blood vessels and enter
tissue space
Phagocytosis (eater), contain several lysosomes
Lead to inflammatory response
Lifespan : 7hrs in blood, 4-5 days in tissues
Neutrophilia
Exercise,Pregnancy
Acute infection
Tissue destruction
Acute stress
Neutropenia
Hypoplasia of the bone marrow
Typhoid fever
Eosinophils








10-14μm
Large, coarse, numerous granules, stained deep red by
eosin
Nuclei with two lobes
1-4% of WBC count
Half life 1 - 8hrs, then enter tissues (few weeks)
Found in lining of respiratory and digestive tracts
Important functions involve protections against
infections caused by parasitic worms and involvement
in allergic reactions
Secrete anti-inflammatory substances in allergic
reactions
Eosinophilia
Infections – parasitic
Allergic conditions – asthma, atopic dermatitis,
Drug reactions – aspirin, sulphonamides, cephalosporins
Neoplasms – leukemia, lymphomas
Eosinopenia
ACTH
Corticosteroids
Bone marrow depression
Basophils








10-14μm
Least numerous - 0.5-1%
Densely packed with large granules, stained
purplish black by basic dyes
Contain histamine,serotonin,heparin—
inflammatory chemical
Nucleus 2-3 lobed
Lifespan – few hours
Diapedesis—Can leave blood vessels and enter
tissue space
Degranulation may protect us from some
parasitic infections eg scabies
Basophilia
Allergy
Tuberculosis
Chicken pox
leukemia
Basopenia
Bone Marrow depression
After glucocorticoid administration
Monocyte










Largest of WBCs (10-18μm)
Dark kidney/ bean shaped nuclei
Highly phagocytic
Precursors of tissue macrophages
Avg intravascular stay 3 days
In tissues undergo differentiation to form
macrophages
Phagocytose foreign particle
Removal of damaged and dying cell debris
Stimulation of granulopoeisis
Interaction with antigen and lymphocytes in
immune response
Monocytes and macrophages
Monocytosis
Tuberculosis
Malaria
Leukemia
Syphilis
Monocytopenia
Glucocorticoids
Hypoplastic bone marrow
Lymphocyte






Smallest WBC
Large nuclei/small amount of cytoplasm
Show variation in size (small :7-10μm/large: 10-14μm)
Account for 25% of WBC count
Two types—T lymphocytes—attack an infect or
cancerous cell, B lymphocytes—produce antibodies
against specific antigens (foreign body)
Lifespan highly variable
Lymphocytosis
Leukemia
Viral infections
Lymphocytopenia
Hypoplastic marrow ------aplastic anaemia, radiation
AIDs
WBC Numbers





Doctors look at WBC numbers.
If number goes up there is some kind of infection and
surgery might be needed.
Clinics will count the number of WBC’s in a blood
sample, this is called differential count.
A decrease in the number of white blood cells is
leukopenia
An increase in the number of white blood cells is
leukocytosis.
Formation of WBC’s
Formed from pluripotent hematopoetic stem cells
By progressive proliferation and differentiation some THSC
get commited to form specific leucocyte
Bacteria and macrophages stimulate macrophages and
monocytes to produce IL-1 and TNF-α which in turn stimulate
other cells to produce colony stimulating factors
Regulation of granulopoesis
Regulated with great precision in healthy individuals
Why is it necessary?
Cytokines –proteins released by cells that act as intercellular
mediators
Growth factors-------------- acting on stem cells
immature committed cells
specific growth factor
Growth factor Sources
Cell line stimulated
IL-1
Macrophages
Early progenitors
TNF
Macrophages
Effects same as IL-1
IL-3
T lymphocytes
Granulocyte,
monocyte,erythrocyte ,
megakaryocyte
IL-4
T lymphocyte
Basophil
IL-5
T lymphocyte
Eosinophil
SCF
Multiple cell types
Granulocyte, monocyte,
erythrocyte, megakaryocyte
G-CSF
Fibroblasts,
endothelial cells
Granulocyte
GM-CSF
Fibroblasts,
endothelial cells
Granulocyte, monocyte,
erythrocyte , megakaryocyte
Leukemia
Uncontrolled producrion of WBC’s by cancerous mutation of
myelogenous or lymphogenous cell
Greatly increased number of abnormal WBC’s
Undifferentiated WBC’s
Two types: lymphocytic and myelogenous
Acute/chronic
Spread of cancerous cells to sorrounding bone,spllen,
lymph node, liver
Development of infection/ bleeding tendency, anemia
Rapid deterioration of normal protein tissues of the body.
Metabolic starvation
Leukemoid reaction