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

Objectives 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

Leukocytes White blood cells or WBCs Mobile units of body’s immune defense system Immune 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

Leukocytes Colorless – lack hemoglobin WBC can be stained and seen under microscope Vary in structure, function, and number Somewhat larger than erythrocytes 5 different types of circulating leukocytes Neutrophils Eosinophils Basophils Monocytes Lymphocytes

WBC 5 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

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.

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.

CLASSIFICATION GRANULOCYTES AGRANULOCYTES

Percentage of Total WBC Concentration (Normal Counts) Cell Approximate Normal range (/µL) Percentage of Total WBC Total WBC 4000-11000 - - - Granulocytes Neutrophils Eosinophils Basophils 3000-6000 150-300 0-100 60-70% 1-4 % 0.25 - 0.5% Agranulocytes Lymphocytes 1500-4000 20-40% Monocytes 300-600 2-8%

Site of Formation - WBC Ultimately 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

Myeloblast Erythroblast Monoblast

GENERAL CHARACTERISTICS OF WBCSs

Life span of leukocytes: Granulocytes  4-8 hours (1 day) Monocytes  10-20 hours (3 days) Lymphocytes  months (100-300 days) Macrophages Months- years

NEUTROPHILS Most Abundant WBCs 60-70 % Size: 14-16 µm Nucleus: Multilobed 2-5 lobes Function: Phagocytosis

DEFENSIVE PROPERTIES OF NEUTROPHILS Diapedesis Chemotaxis Phagocytosis & Digestion

NEUTROPHILS

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

Eosinophils count, High eosinophil count: Parasitic (hook worm, ascaris, bilharzia) Allergic (asthma, rhinitis, drug reaction) Allergic Dermatological diseases

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.

MONOCYTES Nucleus- single large,kidney shape Cytoplasm-No Granules but Vacoules Size: 16-20 µm Function-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 years Become professional phagocytes

TISSUE MACROPHAGE SYSTEM Examples are: - 1. Tissue macrophages in Skin and Subcutaneous tissues (Histiocytes) 2. Macrophages of Lymph Nodes 3. Alveolar macrophages 4. Tissue macrophages in Liver sinuses (Kupffer Cells) 5. Macrophages of Spleen & Bone marrow 6. Microglia in Brain

Tissue macrophages in Liver sinuses

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 programmed 2 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

Lines of Defense Response 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

IMPORTANT TERMS Leukocytosis – Increase in WBC count Leukopenia - Decrease in WBC count Neutrophilia - Increase in neutrophil count Leukemias – Abnormal Increase in immature WBC count (blood cancer). Pus

Formation of Pus Dead Neutrophils Dead Macrophages Necrotic tissue

LEUKEMIA Leukemia is cancerous condition WBC count may be 100,000-500,000/mm3 Most of WBC are immature, therefore, they can not perform normal function of defense Infections are common Bone 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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