This document provides information about white blood cells (leukocytes): - It describes the main types of leukocytes - granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). It details their morphology, counts, functions and factors that cause their levels to vary. - The formation (leukopoiesis), regulation and lifespan of white blood cells is explained. Key processes like phagocytosis, respiratory burst and neutrophil recruitment are summarized. - Specific details are given about each type of leukocyte - their size, nuclear morphology, cytoplasmic granules, functions and causes of increased/decreased counts.

1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
LEUCOCYTES
WHITE BLOOD
CELLS.

2. OBJECTIVES.
 Types of WBC and their counts
 Formation of WBC
 Morphology, life span, functions and
variations in count of WBC
 Applied aspects.
Sunday, June 19, 2016

3. INTRODUCTION
• Crucial in the body’s defense against pathogens
• These are complete cells, with a nucleus and organelles
• They lack Hb so they are colorless (i.e. white)
• Able to move into and out of blood vessels (Diapedesis)
• Can respond to chemicals released by damaged tissues
(Chemotaxis)
• Some are capable of Phagocytosis

4. TYPES OF LEUKOCYTES
• Granulocytes
• Granules in their cytoplasm
can be stained
• Biologically active
substances involved in
inflammatory and allergic
reactions.
• Neutrophils, Eosinophil,
and Basophils

5. TYPES OF LEUKOCYTES
• Agranulocytes
• Lack visible
cytoplasmic
granules
• Lymphocytes and
Monocytes

6. TYPES OF LEUKOCYTES

7. LEUKOCYTE LEVELS IN THE
BLOOD
• Normal levels =4,000 to 11,000 cells/mm3
• Abnormal leukocyte levels
• Leucocytosis
• Above 11,000 leukocytes/ml
• Generally indicates an infection
• Leucopenia
• Abnormally low leukocyte level
• Commonly caused by certain drugs

8. Figure 19.11
WHITE BLOOD CELLS

9. CONCEPT OF POOL
 There are 3 different areas in our body where different
WBCs reside
1. Marrow pool: 90% neutrophils
2. Blood pool: 3%
3. Tissue pool: 7%
 Genesis of WBCs: Leucopoiesis
 In bone marrow PHSC (Pluripotential hemopoietic→
stem cells) differentiates committed stem cells→ →
CFU-GM
 Granulocytes & monocytes are formed only in bone marrow
 lymphocytes & plasma cells are produced in various
lymphogenous tissues

10. GENESIS OF WBCS
(LEUKOPOIESIS):

11. REGULATION OF
LEUCOPOIESIS
Granulopenia or Dead granulocytes and monocytes
Release
G-CSF
M-CSF
GM-CSF
Interleukins IL-1, IL-3
Stimulate
Bone Marrow
Normal counts inhibit increased formation
Granulocytes, Monocytes/Macrophages
 Prostaglandins: Monocytes, Lactoferrin
 Cytokines: glycoproteins formed by monocytes and T- lymphocytes :

12. NEUTROPHILS:
 Size:10-14 µm in diam.
 Nucleus:
1. Multilobed (1-6 lobes) therefore
called polymorphnuclear
leucocytes.
2. Young cell have single horse shoe
shaped nucleus.
3. As the cells grow older nucleus
becomes multilobed. Lobes are
connected with one another by
chromatin threads.
4. Arneth count:
 Cytoplasm: contains neutrally stained
granules
 average half-life in the circulation is 6
hours

13. NEUTROPHILS:
4 types of granules are present
1. Primary/ Azurophilic granules: less in
no. enzymes like
i. myeloperoxidase, (produces HOCl for
killing bacteria).
ii. lysosomal granules containing acid
hydrolases, which can digest bacteria,
elastase, proteinase, α-1 antitrypsin
iii. Antimicrobial proteins like
cathepsin-G, Defensins- α, β
iv. Tissue destruction during
inflammation

14. 2. Secondary /Specific/peroxidase
negative granules: more numerous.
Contain
i. Lactoferrin-antibacterial
ii. Gelatinase, lysozyme- microbicidal,
Vit B12binding protein &
iii. Components of enzyme system that
produce free radicals like H2O2,
which kills the microbes.
iv. Substances that facilitates
chemotaxis.
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15. NEUTROPHILS:
3. Tertiary granules: Gelatinase, alkaline phosphatase and
cytochrome-b
4. Secretory Granules: secretory vesicles contain CD3, phospholipase
and tyrosine kinase
Toxic granules: During severe infections toxic coarse granules are
seen.
 Functions:
1. Phagocytosis:
2. Reaction of inflammation: release leukotrienes, prostaglandins,
thromboxanes
3. Febrile Response: They contain fever producing substance,
endogenous pyrogen which is an important mediator of febrile
response to bacterial pyrogens.

16. NEUTROPHILS:
 These enzymes act
 in a cooperative fashion with the O2
 –, H2O2, and HOCl formed by the action of
the NADPH oxidase and
 myeloperoxidase to produce a killing zone
around the activated neutrophil.

17. PROCESS OF PHAGOCYTOSIS
(CELL EATING)
Phagocytes engulf and kill microorganisms
Steps of Phagocytosis:
1. Margination
2. Emigration and Diapedesis
3. Chemotaxis
4. Recognition and attachment(Opsonization)
5. Engulfment and creation of phagosome
6. Fusion of phagosome with lysosome
7. Destruction and digestion
8. Residual body → Exocytosis

18. NEUTROPHIL RECRUITMENT
Selectins/Addressins ß2 –Integrin / ICAM-1
flow rolling adhesion transmigration
inflammatory
mediators
Tissue Injury
(e.g. Bacterial infection)
chemoattractant
(e.g. IL-8, C5a),
leukotrienes
• phagocytosis
• oxidant production
• lysosomal granules
endothelium

19. OPSONIZATION AND PHAGOCYTOSIS
 IgG and C3b opsonin proteins
 Fc receptors for antibody
 Complement receptors: (e.g. C3b)
 Other
 receptors for collectins (eg. mannose-binding
protein)
 G protein-mediated responses, increased
motor activity of the cell, exocytosis,
respiratory burst

20. OPSONIZATION

22. RESPIRATORY BURST: NADPH
OXIDASE
NADPH oxidase activation

23. Superoxide anion: O2-
Hydrogen peroxide: H2O2
Hydroxyl radical: OH .
Hypochlorous acid: HOCl
Myeloperoxidase = MPO
O2 + e-
2O2- + 2H+
H2O2 + Fe2+
H2O2
O2-
H2O2 + O2
OH + OH- + Fe3+
HOCl + OH-MPO
REACTIVE OXYGENREACTIVE OXYGEN
METABOLITESMETABOLITES

24. VARIATION IN NEUTROPHIL
COUNT:
 Neutrophilia: in↑
neutrophils>10000/mm3
 A. Physiological
1)After Exercise,
2)After injection of epinephrine,
3)Pregnancy, menstruation,
parturition & lactation,
4)Newborn,
5)After meals,
6)Mental or emotional stress
 B. Pathological
1)Acute pyogenic (pus forming)
bacterial infections,
2) Acute Rheumatic fever, Gout
2)Following tissue destruction,
i) Burns
ii) After hemorrhage,
iii) myocardial infarction, iv)
After surgery
v) poisoning by lead, mercury,

25. NEUTROPENIA: IN NEUTROPHILS↓ :
< 2500/mm3
 In children
 Typhoid, paratyphoid fever
 Viral infection
 Malaria
 Aplasia of bone marrow
 Bone marrow depression due to
 Chloromycetin, cytotoxic drugs
 X-rays & radiations
 Chemical poisons like arsenic

26.  Size:10-14 µm in diam. (2%)
 Nucleus:
1. Usually (85%) cells ‘bilobed’.
2. Lobes are connected with one
another by chromatin threads
thus producing spectacle
appearance.
3. Remaining 15% cells have
trilobed nucleus.
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27.  Cytoplasm:
 i. Acidophilic, appears light pink in
colour after staining Granular
 ii. Granules
1. Coarse, stain bright brick red with
acidic (eosin) dye.
2. Granules do not cover the nucleus.
3. They contain very high peroxidase
content (histaminase), lysozymes,
ECF-A & Major Basic Protein (MBP)
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28. FUNCTIONS:
1. Mild Phagocytosis: less
motile than
neutrophils
2. Parasitic infestations:
 Major Basic Protein- Larvicidal
 Eosinophil Cationic Protein-
bactericidal & major destroyer of
helminths.
 Eosinophil Peroxidase –
destruction of helminths,
bacteria & tumour cells

29. FUNCTIONS:
3. Allergic reaction:
bronchial asthma & hay
fever
 Detoxifying inflammation
inducing subs like bradykinin,
histamine
 inhibit mast cell degranulation
 phagocytose & destroy Ag-Ab
complexes
4. Immunity:
specially abundant
in the mucosa of
respiratory tracts,
GIT, urinary tract,
where they
provide mucosal
immunity
Sunday, June 19, 2016

30. VARIATION IN EOSINOPHIL
COUNT
 Eosinophilia: in↑
eosinophils
 Causes are:-
1)Allergic conditions e.g.
bronchial asthma, hay
fever, filariasis
2) Parasitic infestation,
trichinosis &
schistosomiasis e.g.
worms (hookworm,
roundworm & tapeworm),
3) Skin disease like utricaria.
 Eosinopenia: in↓
eosinophils
 Causes are:-
1) ACTH & steroid therapy
2) Stressful conditions, &
3) Acute pyogenic infections

31. BASOPHILS:
 Size:10-14 µm in diam.
 Nucleus:
 irregular bilobed, often ‘S’
shaped & its boundary is not clear because
of overcrowding with coarse granules.
 Cytoplasm: Is slightly basophilic & appear
blue, it is full of granules.
 Granules:
 coarse, stain deep purple/blue
 Plenty, completely fill the cell & overload the
nucleus
 Contain heparin, histamine & 5HT.

32. FUNCTIONS
1. Mild phagocytosis
2. Role in allergic reaction:
Basophils release histamine,
bradykinin, slow reacting substance of anaphylaxis
(SRS-A) & serotonin (5HT). These substances
cause local vascular & tissue reactions that
cause many allergic manifestations.
3. Prevents spread of Allergic inflammatory process
4. Liberates heparin which
i. Acts as anticoagulant & keeps blood in fluid
state.
ii. Activates the enzyme lipoprotein lipase which
removes fat particles from the blood after fatty
meal.

33. VARIATION IN BASOPHIL COUNT:
 Basophilia: in basophil↑
count >100/mm3
 Causes are:-
1) Viral infections, e.g.
influenza, small pox &
chicken pox
2) Allergic diseases
3) Chronic myeloid
leukemia.
 Basopenia: in basophil↓
count
 Causes are:-
1) Corticosteroid therapy,
2) Drug induced reactions &
3) Acute pyogenic infections

35.  2nd
line of defence.
 Size: Largest WBC 18-20 µm.
 Nucleus:
1. Is large single, eccentric in
position (present on one side of
the cell).
2. It is notched/ indented (kidney shaped)
3. It has reticulated chromatin network.
 Cytoplasm:
i. Is abundant, pale blue & usually clear with no
granules.
Granules:
i. Sometimes contain fine purple dust like
granules called Azur granules

36. FUNCTIONS
1. Role in phagocytosis:
These are powerful phagocytes & capable
of phagocytosis as many as 100 bacteria. They also have
ability to engulf large particles such as RBCs & malarial
parasites.
2. Role in tumor immunity: kill tumor cells after sensitization by
lymphocytes, play a key role in the lymphocyte – mediated
immunity.
3. Synthesis of Biological Substances:
 synthesis complement, prostaglandin E & clot promoting factors
 Interleukin1 ii) Hemopoietic factors iii) TNF-α,
 iv)Binding proteins like transferrin,v) lysosomes,
 Proteases vii) Acid hydrolases

37. VARIATION IN COUNT
 Monocytosis: in m↑ onocyte
count
 Causes are:-
1) Certain bacterial infections,
e.g. tuberculosis, syphilis &
subacute bacterial
endocarditis
2) Viral infections
3) Protozoal & rickettsial
infections, e.g. malaria, kala
azar
 Monocytopenia: in↓
monocyte count
 Causes are:-
It is rare, may be seen in
hypoplastic bone marrow.

38.  2 types of lymphocytes
 Morphologically: small & large
 Functionally: T & B lymphocytes
 Small lymphocytes: 7-10 µm
Nucleus rounded, cytoplasm: just rim is seen.
Older cells.
 Large lymphocytes: 10-14 µm Nucleus is big
with indentation, definite cytoplasm is seen.
Precursor of small lymphocyte.

39. Functional subtypes: small lymphocytes are broadly
classified into
1. B lymphocyte: processed in the bone marrow, concerned
with the humoral immunity.
2. T lymphocyte: processed in thymus, concerned with the
cellular immunity
Functions of B lymphocytes: B lymphocytes & their
derivatives, plasma cells are responsible for humoral
(antigen mediated) immunity. They produce antibodies
(gamma globulins).This is major mechanism against the
invading organisms

40.  by direct action
 by making them inactive by agglutination, precipitation,
neutralization or lysis and
 through complement system
Functions of T lymphocytes:
T lymphocytes are responsible for cellular (Cell mediated/ T
cell) immunity. T cell immunity play imp defensive role against:
 viral & bacterial infections
 tumor cells
Provide a specific immune response to
infectious diseases.

41. VARIATION IN LYMPHOCYTE COUNT
 Lymphocytosis: in↑
lymphocyte count
Physiological
1. healthy & young children
2. female during
menstruation
Pathological:
1. Chronic infections like tuberculosis,
hepatitis & whooping cough
2. Lymphatic leukemia
3. Viral infections like chicken pox
4. Autoimmune disease like
thyrotoxicosis
 Lymphocytopenia: ↓
in lymphocyte count
1. Patients on
corticosteroid &
immunosuppressive
therapy
2. Hypoplastic bone
marrow
3. Widespread irradiation
4. Acquired Immuno
Deficiency syndrome
(AIDS)

42. LIFE SPAN OF WBCS
 Granulocytes:
 after released from bone marrow, 4-8 hours circulate in
blood
 & another 4-5 days in the tissues.
 Survive only for few hours in serious infection
 Monocytes:
 72 hrs in blood.
 Once in tissue they swell up to much larger size to become
tissue macrophage in this form they can live for month.(3)→
 Lymphocytes:
 Life span for week or months depending on body’s need.
 They continually circulate in blood & move from blood to
tissues & from tissues to blood and again blood to tissues.

43. LEUKAEMIAS
 Malignant diseases
 Increase in total WBC count->50,000/mm3
 Presence of immature wbcs in peripheral
blood
Types of LeukaemiasTypes of Leukaemias
1. Acute myeloblastic leukaemia (AML)
2. Acute lymphoblastic leukaemia (ALL)
3. Chronic myeloid leukaemia (CML)
4. Chronic Lymphoid leukaemia (CLL)

44. Thank
You