White Blood cells
Most dreaded enemies…….always exposed
Multiple defense mechanisms
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
White blood cells/leukocytes
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
Absence of granules Agranulocyte
Neutrophils Eosinophils
Basophils
Monocytes
Lymphocytes
50-70%
1-4%
0-1%
2-8%
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
Neutropenia
Exercise,PregnancyAcute infectionTissue destructionAcute stress
Hypoplasia of the bone marrowTyphoid 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
EosinopeniaACTH
Corticosteroids
Bone marrow depression
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
Basophils
Basophilia
Basopenia
AllergyTuberculosisChicken poxleukemia
Bone Marrow depressionAfter glucocorticoid administration
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
Monocyte
Monocytes and macrophages
Monocytosis
Monocytopenia
GlucocorticoidsHypoplastic bone marrow
TuberculosisMalariaLeukemiaSyphilis
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
Lymphocyte
Lymphocytosis
Lymphocytopenia
LeukemiaViral infections
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 andmonocytes to produce IL-1 and TNF-α which in turn stimulateother 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 intercellularmediators
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
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