DIFFERENTIAL LEUCOCYTE COUNT (DLC)

Dr. SYED AFTAB OMARAlMaarefa College

HMIM BLOCK 224

Objectives

• Describe the morphological characteristics of each white blood cell.

• Identify the different blood cells in the blood smear.

• Differentiate between neutrophils, eosinophils, basophils, monocytes and lymphocytes.

• Describe the functions of each WBCs.• List the conditions in which their count

increases and decreases.

Apparatus & materials

Microscope

Glass slides

Lancet

Alcohol swab

Leishman’s stain

Distilled water

Smear Preparation

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Types of White Blood Cells• White blood cells:• Are leukocytes

•There are five types of WBCs in two categories:• Granulocytes

• Neutrophils• Eosinophils• Basophils

• Agranulocytes• Lymphocytes• Monocytes

Blood smear under microscope

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Neutrophils•Size – 10-14 µm. •Multilobed nucleus•Light purple (neutral) granules •Other names is Polymorphonuclear leukocyte• Phagocytic in function• Normal range = 50% - 70%• Elevated in acute bacterial

infections

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Eosinophils• Size – 10-15 µm•Coarse red color granules •Bi-lobed nucleus• Defend against parasitic worm infestations• Normal range 1% - 6%• Elevated in parasitic worm infections and allergic reactions

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Basophils•Size – 10 – 15 µm •Bilobed nucleus•Deep blue granules covering the whole nucleus• Release histamine • Release heparin • Normal range- Less than 1%

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Monocytes• Largest of all blood cells•Size – 12 – 20 µm •Spherical, kidney-shaped, oval or lobed nuclei•No visible granules• May leave bloodstream to become macrophages• Normal range - 2% - 10% • Phagocytize bacteria, dead cells, and other debris•Increase count – in chronic infections eg. Tuberculosis

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Lymphocytes•Size – 7-9 or 10-15 µm •Slightly larger than RBC• Large spherical nucleus surrounded by thin rim of cytoplasm•No visible granules •Normal range -20% - 40% •T cells and B cells

• Both important in immunity

• B cells produce antibodies•T cells involved in cell mediated immunity

• Increased count is seen in viral infections, chronic infections

Counting directions

Counting 100 cellsN N M N N N N E L N

N N N L N N Neutrophil = %

Eosinophil = %

Basophil= %

lymphocyte = %

Monocyte = %

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WBC count decreases in bone marrow suppression due malignancy, radiation, chemotherapy or any genetic disorder