WHITE BLOOD CELLS (WBCs) Leukocytes HMIM BLOCK 224 Lecture - 4 DR. ZAHOOR

WHITE BLOOD CELLS (WBCs)Leukocytes

HMIM BLOCK 224

Lecture - 4DR. ZAHOOR

ObjectivesObjectives

Recognize the different types of WBCs

Write the normal values of the WBCs

Summarize the functions of each WBC

Predict the changes in WBCs in different clinical conditions

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Leukocytes White blood cells or WBCsMobile units of body’s immune defense systemImmune system

Made up of leukocytes, their derivatives, and variety of plasma proteins

Recognizes and destroys or neutralizes materials within body that are foreign to “normal self”

Functions Defends against invading pathogens Identifies and destroys cancer cells that arise in body Functions as a “cleanup crew” that removes worn-out

cells and tissue debris

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LeukocytesColorless – lack hemoglobin WBC can be stained and seen under

microscopeVary in structure, function, and numberSomewhat larger than erythrocytes5 different types of circulating leukocytes

NeutrophilsEosinophilsBasophilsMonocytesLymphocytes

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WBC5 types of Leukocytes can be divided into 1) Granulocytes ( Polymorpho nuclear

granulocytes) 1- Neutrophils 2- Eosinophils 3- Basophils 2) Non- Granulocytes ( Mononuclear

agranulocyte) 4- Monocytes 5- Lymphocytes

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WBC 1- Granulocytes ( Polymorpho nuclear granulocytes)

Polymorpho nuclear granulocytes can be distinguished by looking at their nucleus lobes, and granules present in cytoplasm and on the basis of dye which they take up.

1. Eosinophils – Nucleus bilobed, granules take acidic dye and look red.

2. Basophil – Nucleus segmented, granules take basic dye and look blue.

3. Nuetrophil – Nucleus 2-5 lobes,granules take both acidic and basic dye and look purple or light pink.

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WBC 2. Non- Granulocytes (Mononuclear agranulocyte)

Monocyte and Lymphocyte are called Mononuclear Agranulocyte. Mononuclear (single nucleus), Aganulocytes (cells having no granules)

-Monocyte – is large cell having oval or kidney shape nucleus, No granules in cytoplasm.

-Lymphocyte – has large spherical nucleus that occupies most of the cell , No granules in cytoplasm. 7

GRANULOCYTES AGRANULOCYTES

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Cell ApproximateNormal range(/µL)

Percentage of Total WBC

Total WBC 4000-11000 - - -

Granulocytes

Neutrophils Eosinophils Basophils

3000-6000150-3000-100

60-70%1-4 %

0.25 - 0.5%

Agranulocytes

Lymphocytes1500-4000 20-40%

Monocytes 300-600 2-8%

Concentration (Normal Counts)

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Site of Formation - WBCSite of Formation - WBCUltimately originate from same

undifferentiated multipotent stem cells in red bone marrow

Granulocytes and monocytes are produced only in bone marrow

Lymphocytes are originally produced in bone marrow but most new lymphocytes are actually produced in lymphoid tissues such as lymph nodes and tonsils

Total number of white cells and percentage of each type may vary considerably to meet changing defense needs

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Myeloblast

Erythroblast

Monoblast

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Granulocytes 4-8 hours (1 day)Monocytes 10-20 hours (3 days)Lymphocytes months (100-300 days)

Macrophages Months- years

Life span of leukocytes:

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NEUTROPHILSMost Abundant WBCs 60-70 %

Size: 14-16 µmNucleus: Multilobed 2-5 lobes

Function: Phagocytosis

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DEFENSIVE PROPERTIES OF NEUTROPHILS

1. Diapedesis2. Chemotaxis3. Phagocytosis &

Digestion

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NEUTROPHILS

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Eosinophil Size 12 -14 µm Nucleus – Bilobed Granules contain arginine rich protein, which take

acid dye (eosin) Function: 1. in allergic condition. 2-Phagocytosis Chemotaxis: attracted towards chronic inflammation

Neutralises allergic products such histamine, 5-HT, bradykinin (allergic disease of skin &lungs)

Phagocytosis is same as neutrophil, but less efficient

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Eosinophils count,High eosinophil count:

Parasitic (hook worm, ascaris, bilharzia)Allergic (asthma, rhinitis, drug reaction)Allergic Dermatological diseases

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Basophils Size 12 -14 µm Nucleus – Segmented in center Granules contain polysaccharide granules which take

basic dye methylene blue therefore they look blue in color.

Function

Its granules release heparin, histamine, 5HT.

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MONOCYTESNucleus- single large,kidney shape

Cytoplasm-No Granules but Vacoules

Size: 16-20 µmFunction-Phagocytosis.Life span: 10-20 hours in blood (3 days)

Monocytes Emerge from bone marrow while still

immature and circulate for day or two before settling down in various tissues in body

Mature and enlarge in resident tissue and become known as macrophages (“large eaters”)Life span of Macrophage can range from

several months to yearsBecome professional phagocytes

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TISSUE MACROPHAGE SYSTEM

Examples are: -1. Tissue macrophages in Skin and

Subcutaneous tissues (Histiocytes)2. Macrophages of Lymph Nodes3. Alveolar macrophages4. Tissue macrophages in Liver

sinuses (Kupffer Cells)5. Macrophages of Spleen & Bone

marrow6. Microglia in Brain

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Tissue macrophages in Liver sinuses

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LYMPHOCYTES Nucleus – single, rounded, occupies

most of the cell Cytoplasm - No Granules Size: 10-16 µm Live about 100 to 300 days Function – immunity.-Number increases in viral infection

Lymphocytes Provide immune defense against targets for

which they are specifically programmed2 types of lymphocytes

B lymphocytes Produce antibodies which circulate in blood Responsible for antibody-mediated or humoral immunity

T lymphocytes Do not produce antibodies Directly destroy specific target cells by releasing

chemicals that punch holes in the victim cell (cell-mediated immunity)

Target cells include body cells invaded by viruses and cancer cells

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Lines of DefenseResponse to Inflammation

1st line of defense in Tissue – Tissue macrophages & Physical Barriers

2nd line of defense – Neutrophil Invasion of the inflamed area

3rd line of defense – Monocytes –macrophage invasion of inflamed area

4th line of defense – Increased production of granulocytes and Monocytes by Bone marrow

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IMPORTANT TERMSLeukocytosis – Increase in WBC countLeukopenia - Decrease in WBC countNeutrophilia - Increase in neutrophil

countLeukemias – Abnormal Increase in

immature WBC count (blood cancer).Pus

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Formation of Pus

Dead Neutrophils Dead Macrophages Necrotic tissue

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LEUKEMIALeukemia is cancerous conditionWBC count may be 100,000-500,000/mm3

Most of WBC are immature, therefore, they can not perform normal function of defense

Infections are commonBone marrow produces increase number of

WBC, therefore, there is decrease RBC formation leading to anemia

Decreased platelet formation leading to bleeding

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Thank youThank you

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