White Blood Cells
WBCs
White Blood cells are also known as
Leucocytes as they are colorless due to
lack of Haemoglobin.
There are about 6000-8000mm of
WBC for 1ml of blood.
WBC’s
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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.
Leukocytes
1-Phagocytes
-Granulocytes ( Neutrophils,
Eosinophils, Basophils)
-Monocytes
2-Immunocytes
Lymphocytes
Formation of WBC’s
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Leucocytes are formed in the red
marrow of many bones.
They can also be formed in lymphatic
tissue.
They live for about 13-20 days.
Granulopoiesis
-Bone marrow
-Common precursor
-Normally, BM storage 10-15 times the
number of granulocytes than peripheral
blood
-Stay for 6-10 hrs then move to their tissues
to perform their phagocytic functions.
Granylopoiesis
Many growth factors are involved in:
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Maturation of these cells
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Proliferation and Differentiation
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Function
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Interleukin-1 (IL-1),IL-3,IL-6 +
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GM-CSF (granulocyte-macrophage
colony-stimulating factor)

eosinophil (IL-5)
Growth factors
Infection
Causes an Induction of GF
productions
Increases No. of granulocytes &
Monocytes
Type of WBC’s
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Granulocytes—have large
granules in their cytoplasm
Neutrophils
 Eosinophils
 Basophils
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Granuloctyes
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Neutrophils
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Stain light purple with neutral dyes
Granules are small and numerous—course
appearance
Several lobes in nucleus
65% of WBC count
Highly mobile/very active
Diapedesis—Can leave blood vessels and
enter tissue space
Phagocytosis (eater), contain several
lysosomes (janitor)
Agranulocytes
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Monocytes
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Largest of WBCs
Dark kidney bean shaped nuclei
Highly phagocytic
Granulocytes:
Neutrophils/Eosinophils/Basophils
•Classified according to cell morphology and cytoplasmic staining
•Neutrophils: stains with BOTH acid and basic dyes. called
‘PMN’ for lobed nucleus; 50% of circ leukocytes
•Eosinophils: stain with ACID dye (Eosin-red); bilobed nucleus
1-3% of leuko’s.
•Basophils: stain with BASIC dye (Methylene blue); <1% of
leuko’s
Neutrophils
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Circulate in peripheral
blood 7-10 hr before
migrating into tissue; live
only a few days
“front line of innate
defense”
Attracted by chemotactic
factors
Active phagocytes;
digestive enzyme held in
1° and 2° granules
Use both O2-dep and O2indep digestive mech’s
Produce high levels of
defensins
Neutrophil
Granulocytes
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Eosinophils or Acidophils:
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Large, numerous granules
Nuclei with two lobes
2-5% of WBC count
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
Eosinophils and Basophils
Eosino’s
Like Neutrophils,
function in
phagocytosis
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function vs. parasitic
infections

contents of released 
granules damages
parasitic particals.
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Basophils
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Least numerous--.5-1%
Diapedesis—Can leave blood vessels and
enter tissue space
Contain histamine,serotonin,heparin—
inflammatory chemical
Basophils
Types of WBC’s
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Agranulocytes—do not have
granules in their cytoplasm
Lymphocytes
 Monocytes
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Monocytes
 Large
 Large
Pbl
central
oval nucleus
with clumped
chromatin
Monocytes
 Short
time in BM
 20-40hrs
in
circulation
 Move
to tissues,
mature(Macrophages)
& DCs ,carry out their
main functions.
Monocytes & Neutrohpils Functions
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1-Chemotaxis
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( Cell mobilization and
migration)
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Phagocyte is attracted to
Microbes or Inflammation
site
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By chemotactic Substance
from damaged tissues
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By leukocyte adhesion
molecules and tissues
ligands.
Phagocytosis:
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Dead/ damaged cells of
the host or microbes.
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Recognition
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Opsonization
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Destruction
Killing & Digestion:
O2-dependent
O2-independent
pathways
WBC Numbers
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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.
Disorders of Neutrophil & Monocyte
Function
1-Defects of phagocytic cell function
2-Benign disorders
Defects of Phagocytic cell function
-Chemotaxis:
Lazy Leucocyte Syndrome
-Phagocytosis:
lack of opsonization
Hypogammaglobulinaemia
-Killing:
x-linked autosomal recessive chronic
granulomatous disease
Neutrophil leukocytosis
An increase of
Neutrophils count greater
than 7.5*109
Eosinophilic
leucocytosis
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Eosinophilia
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An increase of blood
Es. Above 0.4*109
Basophil leucocytosis
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Basophilia
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An increase of blood Baso.
Above 0.1*109(rare).
Cause: Myloprolifretive disorder.
Monocytosis
A rise in blood monocytes
count above 0.8*109
Neutropenia
A Decrease of normal
neutrophils count below
2.5*109