White blood cells (WBCs), also known as leukocytes, are nucleated cells that perform defense functions in the body. There are 5 main types of WBCs - neutrophils, eosinophils, basophils, lymphocytes, and monocytes. Each type has distinct morphological features and functions. Neutrophils are the most abundant WBC and form the first line of defense via phagocytosis. Eosinophils and basophils are involved in allergic responses. Lymphocytes mediate humoral and cell-mediated immunity. Monocytes differentiate into macrophages and also phagocytose pathogens. WBC counts can become elevated or decreased in various physiological and pathological conditions.

1. WHITE BLOOD
CORPUSCLEs
(LEUkOCYCTES)
Dr. JILSHA

2. CONTENTS
 Introduction
 Normal values
 CLASSIFICATION
 Morphological features
 Functions
 Physiological and pathological variations

3. INTRODUCTION
 Why are they called White Blood Cells ?
After centrifugation, WBCs are found in
the buffy coat, a thin white layer of cells
between the sedimented RBCs and the
plasma.

4. INTRODUCTION…
WBCs are nucleated cells that
perform the defense functions of the
body
They destroy the invading micro-
organisms and destroy abnormal cells
like cancer cells.

5. NORMAL VALUES
Total Leukocycte count – Normal WBC count
:
 Adults : 4000 – 11,000 / mm3 of
blood
 At Birth : 10,000 – 25,000 / mm3
of blood
(count decreases after 2nd week and
reaches the normal adult value at
5 – 10 yrs.)

6. CONTD..
CELL ABSOLUTECOUNT
(/cu.mm)
DIFFERENTIALCOUNT(%)
Neutrophils 3000 - 6000 50 – 70 %
Eosinophils 150 - 300 1 – 4%
Basophils 10 - 100 < 1 %
Lymphocytes 1500 - 2700 20 – 40 %
Monocytes 300 - 600 2 – 8 %

8. VARIATIONS IN WBC COUNT
 Leukocytosis : refers to increase in WBC count
above 11,000 / mm3
Physiological causes :
 Newborn
 Exercise
 Mental stress
 Pregnancy
 After food intake
Pathological Causes
 Acute bacterial infections
 Acute hemorrhage
 Burns
 Tuberculosis

9.  Leukopenia : refers to WBC count
below 4000 / mm3
Causes :
 Typhoid fever
 Starvation
 Viral and protozoal infections
 Bone marrow depression
FACT
Leukemia is a cancerous condition of blood in which the TLC is more than
50,000 / cu.mm ASSOCIATED WITH THE PRESENCE OF IMMATURE
WBCs in the peripheral smear

10. CLASSIFICATION

11. NEUTROPHILS /
POLYMORPHONUCLEAR
LEUKOCYCTEs

12. MORPHOLOGY
 Morphological features of various types of
WBCs are studied under microscope with
Leishman’s staining and hematoxylin –
eosin staining.
Size : 10 – 14 µm diameter
 Nucleus : Young neutrophil – horseshoe
shaped. As the cells grow older nucleus
becomes multi lobed (2-6 lobes). Mature
neutrophil has purple colored nucleus.

13. MORPHOLOGY

14. MORPHOLOGY
 Cytoplasm : Granular, slight bluish in color.
 Granules
 Fine sand like particles
 Take both acidic and basic stains. Hence the
name neutrophils (neutrophilic in nature)
 Contains variety of enzymes like glycosidases,
sulphatases, phosphatases, nucleases,
proteolytic enzymes etc. Hence can lyse any
substance.
 Also liberate histamine and peroxidase
enzymes which helps in killing the ingested
bacteria

15. COOKE’S ARNETHCOUNT

16. LIFESPANANDFATE
 Neutrophils like all other leukocyctes have four
stages in their life :
 Marrow Pool
 Circulation pool : 8 -10 hours
 Marginated pool
 Tissue pool : either destroyed during
phagocytosis or die due to senescence after 4 –
5 days.
 A huge number of neutrophils is also
eliminated daily, mainly into the intestine and
some into the respiratory secretions.

17. FUNCTIONS
 Neutrophils are actively phagocytic.
They are considered as the first line
defense against acute bacterial infections.
They contain a fever producing substance
called endogenous pyrogen which is an
important mediator of febrile response to
bacterial pyrogens.

18. NEUTROPHIL PHAGOCYTOSIS
 Phagocytosis is the process of ingestion
and killing of microbes or a foreign
substance by a phagocyte.
 Steps of phagocytosis :
 Chemotaxis
 Diapedesis
 Adherence
 Ingestion
 Killing

19.  Chemotaxis
 It is the process by which the neutrophils are
attracted towards bacteria at the site of
inflammation.
 It is mediated by chemotactic agents called
chemotaxins. They are usually the microbial
products or chemicals released from
damaging tissues. These include
Leukotriene B4 , Complement proteins like
C5a and C3.
 Neutrophils change their shape and become
amoeboid.
 Leukopoiesis is stimulated and
more neutrophils are produced.

20. Contd..

21.  Diapedesis
 The process by which neutrophils pass
through the capillary endothelial cells to
reach the invader in the tissue is called
diapedesis.
 The activated neutrophils first marginate
(margination and pavementing) and adhere
tightly to endothelial lining with the help of L
– selectins.
 Then, by their amoeboid movement they
squeeze through the space between the
endothelial cells (emigration and
diapedesis)

22. CONTD..

23.  Opsonization and Adherence
 The process by which the bacteria are
made tasty to the phagocyte is called
Opsonization.
 In this process, antigen is coated by
opsonins.
 Immunoglobulin G antibody and
complement proteins are some examples.
 The attachment of membrane of
phagocyte to the membrane of microbe is
called adherence.

24. CONTD..

25.  Ingestion (Endocytosis)
 The membrane of phagocyte extends
projections from both the sides to
encroach on to the microbe. These
extensions are called pseudopodia.
 Pseudopodia finally surround the microbe
and form phagocytic vesicle.
 The phagocytic vesicle fuse with the
lysosome to form phagolysosome.

26. CONTD..

27.  Killing or degradation
 The bactericidal mechanism can be broadly
classified into :
o Non – oxidative and
o Oxidative mechanisms
 Non – oxidative mechanism
 Neutrophil granules contain a variety of anti –
bacterial chemicals such as degradative
enzymes, proteases, defensins, cationic proteins.
 Lysozyme – hydrolyzes the cell wall, Lactoferrin
– sequestrates iron – non –oxidative
components.
 Defensins – kill bacteria by disrupting their
outer membrane and breaking single
strand DNA structure.

28.  Oxidative mechanisms:
 Following this, the cell membrane bound
enzyme NADPH oxidase is activated. This
causes a sharp uptake in O2. This is called
respiratory burst. This leads to formation of
superoxide radical (O2
-) and Hydrogen
peroxide (H2O2) as follows :
 𝑁𝐴𝐷𝑃𝐻 + 𝐻+ + 2𝑂2 → 𝑁𝐴𝐷𝑃+ + 2𝐻+ + 2𝑂2
 2𝑂2
−
+ 2𝐻+ → 𝐻2 O2
 O2 + 𝐻2 O2 → OH - + OH- + O2
 Hydroxyl radical is a very potent bactericidal
agent.

29. CONTD..

30. VARIATIONS
 Neutrophilia
 Exercise
 Cold
 Stress
 Acute pyogenic Bacterial infections
 Burns
 Hemorrhage
 Drugs like epinephrine, glucocorticoids

31. Neutropenia
Typhoid and paratyphoid fever
Malaria
Aplastic anemia
Viral infections like measles,
influenza
Drugs like chloramphenicol,
pheytoin

32. EOSINOPHILS

33. MORPHOLOGY
 Size : 10 – 14 µm diameter
 Nucleus : Bilobed – spectacle shaped.
Purple colored nucleus.
 Cytoplasm : Acidophilic, light pink in color.
 Granules : Coarse, stain bright red with
eosin.
 Granules contain chemicals like:
 Major basic protein
 Eosinophil catonic protein
 Eosinophil derived peroxidase
 Eosinophil derived neurotoxin
 Cytokines

34. MORPHOLOGY

35. FUNCTIONS
 Eosinophils participate in two important
defense mechanisms of the body
 Against helminthic / parasitic infections
 Against allergy
 They attack parasites that are too large to
be engulfed by phagocytosis. The
granules release peroxidase which are
toxic to larvae of parasites.
 Eosinophils collect at the site of allergic
reactions to release enzymes such as
histaminase and thus limit the effects of
inflammatory mediators.

36. VARIATIONS
Eosinophilia :
 Allergic conditions like bronchial
asthma, allergic rhinitis, urticarial
 Parasitic infections like filariasis,
ascariasis
 Tropical pulmonary eosinophilia
 Drug reactions.
 Eosinopenia
 Glucocorticoid therapy
 Cushing’s syndrome

37. BASOPHILS

38. MORPHOLOGY
Size : 10 – 14 µm diameter
Nucleus : Bilobed – S shaped. Purple
colored nucleus.
Cytoplasm : Slight basophilic, blue in color.
Granules : Coarse, stains purple or blue
with methylene blue.
 Granules are plenty and overcrowd the
nucleus.
 Granules contain histamine, heparin,
serotonin and eosinophil chemotactic
factor ( ECF –A ) of anaphylaxis.

39. CONTD..

40. FUNCTIONS
Mild phagocytosis
Liberates histamine and ECF – A
during allergic reaction which leads to
allergic manifestations. Mild urticaria
to severe anaphylactic shock.
Liberates heparin which acts as an
anti – coagulant.

41. VARIATIONS
 Basophilia :
 Chickenpox
 Small pox
 Tuberculosis
 Influenza
 Ulcerative colitis
 Drug and food hypersensitivity
 Basopenia :
 Glucocorticoids
 Hyperthyroidism
 Cushing’s syndrome

42. SUMMARY

43. LYMPHOCYTES

44. morphology
 Lymphocytes are of two types :
 Large lymphocytes : 10 – 14 µm diameter
 Small lymphocytes : 7 – 10 µm diameter
 Nucleus :
 Single, big, Purple colored nucleus.
 Round, oval or indented.
 Central in position and occupies whole of
the cell leaving marginal cytoplasm at one
end of it or all around it.
 Nuclear chromatin is coarse and lumpy.
Cytoplasm : Pale blue, scanty.

45. CONTD..

46. FUNCTIONS
 Fuctionally, lymphocytes are divided into
three categories : B cells, T cells and
Natural killer cells (NK cells).
 B cells : secrete antibodies. Mediates
humoral or antibody – mediated immunity.
 T cells : mediate cell – mediated immunity.
 NK cells : mediate natural and nonspecific
immunity.

47. VARIATIONS
 Lymphocytosis
 Children – relative lymphocytosis
(60%)
 Chronic infections like TB
 Lymphatic leukemia
 Viral infections.
 Lymphocytopenia
 Hypoplastic bone marrow
 AIDS

48. MONOCYTES

49. MORPHOLOGY
 Size : 10 – 18 µm diameter. Largest
of WBCs.
 Nucleus : Single, round or indented,
eccentric, pale staining.
 Cytoplasm : pale blue in color, clear.
 Sometimes contain fine dust like
granules – Azur granules.

50. CONTD..

51. FUNCTIONS
 Monocyte is an active phagocyte. It is the
second line of defense against infections.
 It is an important Antigen Presenting Cell
(APC)
 Monocytes secrete various chemokines
that carry out different physiological
functions.
 Life span : In circulation : 10 – 72 hrs. Then
they enter tissues. Average lifespan is 3
months. In tissues they become tissue
macrophages.

52. VARIATIONS
 Monocytosis :
 Acute monocytic leukemia
 Hodgkin’s disease
 Polycythemia vera
 Malaria
 Kala – azar
 Monocytopenia:
 Aplastic anemia
 Hairy cell leukemia
 Septicemia

53. SUMMARY

54. THANK YOU !