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