BLOOD CELLS Part 2 Dr Mohammed Hussein M

BLOOD CELLS Part 2 Dr. Mohammed Hussein M. B. Ch. B, MSC, Ph. D, DCH (UK), MRCPCH 10: 51 PM

Blood has four major elements: Red blood cells (Erythrocytes) RBC White blood cells (Leukocytes) WBC Platelets (Thrombocytes) Plasma 10: 51 PM

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RED BLOOD CELLS (ERYTHROCTES) 10: 51 PM

KEY FACTS Have no cell organelles Contain haemoglobin Main function is O 2 & CO 2 transport Cell membrane is braced by an actin/spectrin-containing cytoskeleton which maintains shape. • Biconcave shape for high surface area/volume ratio • • 10: 51 PM

WHITE BLOOD CELLS (LEUKOCYTES) 10: 51 PM

WBCs Count 4000 -11000/ µL 1 Liter = 1, 000 µL 4, 000, 000 – 11, 000, 000 /L 4 – 11 × 10: 51 PM 9 10 /L

WBC TYPES 10: 51 PM

Neutrophils 10: 51 PM Lymphocytes Monocytes Eosinophils Basophils

Differential WBC Count • • • Neutrophils Lymphocytes Monocytes Eosinophils Basophils 50– 70% (~ 60%) 20– 40% (~ 30%) 2– 8% (~ 6%) 1 -4% (~ 3%) 0 -2% (~ 1%) (Never Let 60 30 10: 51 PM Monkey Eat 6 3 Banana) 1

Nomenclatures • Neutrophils (has neutrophilic granules) • Eosinophils (has acidophilic granules) • Basophils (has basophilic granules) Granulocytes • Lymphocytes (has no granules) • Monocytes (has no granules) Agranulocytes • Neutrophils = polymorphonuclear leukocytes (PMN) (or polymorphs) because of their multilobed nucleus • Lymphocytes = cells of lymphoid system • Monocytes = has single large nucleus 10: 51 PM

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Neutrophils 10: 51 PM

Neutrophil count • Normally = (50 – 70%) 1. 5 – 10 × 109 /L • > 10 × 109/L = neutrophilia o Bacterial infection o Tissue necrosis (e. g. MI) • < 1. 5 × 109 /L = neutropenia or agranulocytosis 10: 51 PM

Functions 10: 51 PM

• Their primary function is to 1. Ingest and destroy invading microorganisms in tissues 2. They play a central role in the early stages of the acute inflammatory response to tissue injury 3. Are the major constituent of pus 10: 51 PM

Neutrophil Nucleus • The characteristic neutrophil nucleus is composed of 2– 5 distinct lobes, joined to one another by fine strands of nuclear material 10: 51 PM

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Neutrophils contain 3 types of granules Primary granules • similar to lysosomes • contain acid hydrolases • contain myeloperoxidase Secondary granules • specific to neutrophils • most numerous in cell • contents involved with inflammatory response Tertiary granules • contain enzymes secreted by cell • may insert adhesion molecules into cell surface 10: 51 PM

Neutrophils migrate into areas of tissue damage where they have a defensive role 10: 51 PM

Neutrophils have a role in Phagocytosis of bacteria and dead cells 10: 51 PM

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KEY FACTS • One of the myeloid series of white blood cells • One of the granulocyte type of white blood cells • Main role in phagocytosis and bacterial killing • Contains three types of granule in cytoplasm • Cells marked by myeloperoxidase • Increase in number in blood in bacterial infection and inflammation (‘neutrophilia’). 10: 51 PM

Eosinophil 10: 51 PM

• Strongly eosinophilic granules • Eosinophils have a bilobed nucleus 10: 51 PM

Function • Phagocytic – with a particular affinity for antigen–antibody complexes – less microbicidal activity than neutrophils • Protection against parasitic disease 10: 51 PM

Life Cycle • After production in the bone marrow • eosinophils are stored for approximately 8 days before release into the circulation, where they remain for about 8 hours before preferentially migrating to the skin, lungs and GIT where they reside for about 8 days. 10: 51 PM

Eosinophilia (increased numbers of eosinophils) seen in: 1. Parasitic infestation 2. Tissue (and sometimes blood) eosinophil numbers are also increased in certain allergic states: example I. In the nasal and bronchial mucosae in hay fever and asthma II. Adverse reactions to drugs 10: 51 PM

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• Basophils are the least common WBCs. • Large, intensely basophilic, cytoplasmic granules • Two- to three-lobed nucleus (usually obscured by the cytoplasmic granules) 10: 51 PM

• They share a common lineage with tissue mast cells, with which they have many structural and functional similarities. • Both cells have highly specific membrane receptors for the Ig. E produced in response to allergens 10: 51 PM

Basophil 10: 51 PM Mast Cell

• Exposure to allergens results in rapid exocytosis of basophil granules, thereby releasing histamine and other vasoactive mediators, and resulting in an immediate hypersensitivity (anaphylactoid) reaction. • Such a reaction causes allergic rhinitis (hay fever), some forms of asthma, urticaria and anaphylaxis. 10: 51 PM

Monocytes 10: 51 PM

Monocytes Part of a cell network, the Monocyte-Macrophage System (Mononuclear Phagocyte System) 10: 51 PM

Monocyte-Macrophage System (Mononuclear Phagocyte System) 1. 2. 3. 4. 5. 6. 7. 8. 9. The bone marrow precursors (monoblasts and promonocytes) Circulating monocytes Osteoclasts Tissue macrophages, both free and fixed (histiocytes) Kupffer cells of the liver Sinus lining cells of the spleen and lymph nodes Pulmonary alveolar macrophages Free macrophages in synovial, pleural and peritoneal fluid Dendritic antigen-presenting cell 10: 51 PM

Monocytes • Monocytes are large motile, phagocytic cells. • Has a large, elongated nucleus, often assuming kidney or horseshoe shapes 10: 51 PM

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Responsible for generating specific immune responses 10: 51 PM

• In adults and older children lymphocytes are the 2 nd most numerous WBC in the blood: 20– 40% (~ 30%) N: L = 60: 30 • In young children they are the most numerous WBC: 60% (N: L) N: L = 30: 60 10: 51 PM

• Their nuclei are ovoid, with the dense chromatin (Ball shaped) 10: 51 PM

• 97% of circulating lymphocytes are small, but about 3% are large. 10: 51 PM

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Plasma Cells Are formed from B lymphocytes and secrete immunoglobulin 10: 51 PM

WBCs Abnormalities Increased numbers of WBCs appear in the peripheral blood in a variety of disorders and provide a useful clue to underlying disease. For example: • An increase of circulating neutrophils in bacterial infections (neutrophilia) • An increase of circulating eosinophils in parasitic infestations and some allergies (eosinophilia) • An increase in circulating lymphocytes in certain viral infections and whopping cough (lymphocytosis) 10: 51 PM

Platelets (Thrombocytes) Small cell fragments derived from megakaryocytes and are important in haemostasis 10: 51 PM

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Platelet’s granules 1. α- granules: are variable in size and shape and contain: PF 4 (platelet factor 4), v. WF(von. Willebrand Factor) and others. 2. δ- granules: dense granules and are critical for platelet activation and vasoconstriction 3. Lysosomes: containing lysosomal enzymes 10: 51 PM

Function • Platelets aggregate together and degranulate in haemostasis 10: 51 PM

• The normal platelet count is • 150 -400× 109/L 10: 51 PM

Platelets Abnormalities • The normal platelet count is • 150 -400× 109/L • Thrombocytopenia : low platelets count • Thrombocytosis : high platelets count 10: 51 PM

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