Download White blood cells

 WBCs/
Leukocytes are colourless nucleated cell
elements.
 Larger and lesser in number.
 Important in defence mechanism of body.
 WBCs vs RBCs:






Larger in size.
Irregular.
Nucleated.
Many types.
Some are granulated.
Shorter life span.
 Granulocytes:
 Depending



on staining properties
1. Neutrophils. Granules taking both acidic and basic
stains.
2. Eosinophils. Acidic stain.
3. Basophils. Basic stains.
 Agranulocytes:
 Plain


cytoplasm without granules.
1. Monocytes.
2. Lymphocytes.
 Also
called polymorphs.
 Fine small granules in cytoplasm.
 Take acidic and basic stain.
 Nucleus is multilobed.
 Number of lobes depend on age of the cell.
 Younger cells= nucleus is not lobed.
 Older neutrophills= 2-5 lobes.
 Diameter of cells is 10-12 micron.
 Ameboid in shape.
 Larger
coarse granules.
 Stain pink or red with eosin.
 Bilobed/ spectacle shaped nucleus.
 Diameter 10-14 micron.
 Coarse
granules in cytoplasm.
 Stain purple blue with methylene blue.
 Nucleus is bilobed.
 Diameter 8-10 micron.
 Largest
leukocytes with 14-18 micron diameter.
 Nongranulated.
 Nucleus is round, oval, horseshoe shaped, bean
shaped or kidney shaped.
 Nucleus is either in center or pushed to one side.
 Large amount of cytoplasm.
 Nongranulated
cytoplasm.
 Nucleus is oval, bean shaped or kidney
shaped.
 Nucleus occupies whole cytoplasm.
 A rim of cytoplasm may or may not be seen.
 Divided
 1.


on basis of size and function:
Size:
Large lymphocytes: Younger cells. Diameter 10-12 micron.
Small lymphocytes: older cells. Diameter 7-10 micron.
 2.
Function:
T lymphocytes. Cellular immunity.
 B lymphocytes. Humoral immunity.
NORMAL WBC COUNT:
Total WBC count: 4,000- 11,000

 Leukocytosis:

Increase in total WBC count. Can be physiological and
pathological.
 Leukopenia:

Decrease in total WBC count. Pathological.
 Granulocytosis:

Abnormal increase in number of granulocytes.
 Granulocytopenia:

Abnormal reduction in number of granulocytes.
 Agranulocytosis:

Absolute lack of granulocytes. Acute pathological
condition.
 Age:



Infants= 20,000/ cu mm
Children= 10,000-15,000/ cu mm.
Adults= 4,000-11,000/ cu mm of blood.
 Sex:

More in males than females.
 Diurnal

variation:
Minimum in early morning. Maximum in afternoon.
 Exercise:
increase slightly.
 Sleep: decrease.
 Emotional conditions: increase.
 Pregnancy: increase.
 Mensturation: increase.
 Parturition: increase.
 Leukocytosis:

Increase in total leukocytes.
 Leukemia:

Uncontrolled increase in WBCs. Cancer.
 Leukopenia:

Decrease in total WBC count.
 Neutrophelia

Increase in neutrophil count
 Eosinophilia

Increase in eosinophil count
 Basophilia:

increase in basophile count
 Monocytosis:

increase in monocyte count.
 lymphocytosis:

Increase in total lymphocytes.
 Neutropenia:

decrease in neutrophil count.
 Eosinopenia.

Decrease in eosinophil count.
 Basopenia:


Decrease in basophile count.
Monocytopenia:

Decrease in monocyte count
 Lymphocytopenia:

Decrease in lymphocytes.
 Not
constant. Depends upon body demand.
 May be half day to 3-6 months.
 Functions



of WBCs:
Defence of body.
Protection from invading organisms.
Each type of WBC act in different way.
 1.

Squeezing of WBCs through narrow blood vessels.
 2.

Chemotaxis:
Attraction of WBCs towards injured tissues by
chemical substances released at injury site.
 4.

Ameboid movement:
Neutrophils, monocytes and lymphocytes.
 3.

Diapedesis:
Phagocytosis:
Neutrophils and monocytes engulf foreign bodies.
Defence mechanism of body.
 Provide first line of defence along with monocytes.
 Free cells wander freely through tissues.
 Their granules contain enzymes:

Proteases, myeloperoxidases, elastases and
metalloproteinases.
 They destroy the micro-organisms.


Have antibody like anti-microbial peptides:


Cathelicidins and defensins
Membrane contains NADPH oxidase.
Activated by toxic metabolites released from infected
tissues.
 Responsible for bactericidal action of neutrophils.


Secrete platelet-activating factor:

Aggregation of platelets during injury to blood vessels to
prevent excessive blood loss.
 Released
from blood at injury site.
 New cells are produced at the progenitor cells.
 Move by diapedesis towards injury site due to
chemotaxis (chemo attractants).
 They surround the area and adhere to infected tissues.
 Chemo attractants increase the adhesive nature of
neutrophils.
 Make them sticky and attach firmly to infected area.
 1 neutrophil = 15-20 micro-organisms at the same
time.
 They engulf the bacteria and destroy by phagocytosis.
 Rapid
increase in oxygen consumption during phagocytosis
by neutrophils and other phagocytic cells.
 NADPH oxidase is responsible for this phenomenon.
 Radical oxygen is formed O2- combines with 2H+ -> H2O2
 O2-
and H2O2 have potent bactericidal action.
 Dead
WBCs, bacteria, foreign bodies and cellular
debris form whitish yellow fluid at site of injury.
 Toxins from bacteria kill WBCs which are collected
at the centre of infected area.
 Dead cells + plasma leaked from vessels + liquified
tissue cells + RBCs ( from damaged capillaries) =
PUS.
 Defensive
cells against parasites.
 Parasitic infections -> large number of eosinophils
produced and move towards infection site.
 Count also increase during allergic reactions like
asthma.
 Detoxification, disintegration and removal of
foreign proteins.
 Lethal
substances released from granules and
released at the time of exposure to parasites and
foreign proteins are:
 1. Eosinophil peroxidase.

helminths., bacteria and tumor cells.
 2.

Helminths. ballooning
 3.

Eosinophil derived neurotoxins.
Myelinated nerve fibers.
 5.

Eosinophil cationic protein.
10 times more toxic. Complete distension. Neurotoxin.
 4.

Major basic protein.
Cytokines.
Interleukin 4 & 5. increase inflammatory process by
activating eosinophils. Also kill invading organisms.
 Their
number increase during healing process.
 Allergy or acute hypersensitivity reactions.
 Ig E receptors on basophil membrane.
 Rupture and release from their granules:
 1. Heparin:

Prevent intravascular blood clotting.
 2.
Histamine, slow reacting substances of
anaphylaxis, bradykinin and seratonin:


Acute hypersensitivityy reactions
Proteases and myeloperoxidase:

Destruction of micro organisms.
 4.

Cytokine:
Accelerate inflammatory responses and kill micro
organisms.
 Found
along blood vessels.
 Prominently seen in skin, mucosa of lungs, GIT,
mouth, conjunctiva and nose.
 They don’t enter the blood stream.
 Develop in bone marrow and mature in tissues.
 Play important role in hypersensitivity reactions.
 After activation, release chemical mediators into
the interstitium.
 1. Preformed mediators:

Already formed and stored in secretory granules.
 2.

Newly generated mediators:
Absent during resting condition and produced during
activation.
 Largest,
motile phagocytic cells. Wander freely
through all tissues of the body.
 Provide first line of defence along with neutrophils.
 They secrete:



Interleukin 1
Colony stimulating factor
Platelet activating factor.
 Precursors
of macrophages.
 Mature monocytes remain in blood for few hours
then enter the tissues to form macrophages.
 E.g= kuffer cells, alveolar and spleen macrophages.
 Immune
cells
2
types:
 T lymphocytes:

B

Cellular immunity
lumphocytes.
Humoral immunity