Blood Physiology Professor A.M.A Abdel Gader MD, PhD, FRCP (Lond., Edin), FRSH (London) Professor of Physiology, College of Medicine & King Khalid University Hospital Riyadh

Lecture # 4 & 5 Leucocytes White Blood Cells (WBCs) Granulocytes, The Monocyte-Macrophage System

Leucocytes (WBCs) General Characteristics & types of WBCs Genesis (Production) of WBCs Life Span of WBCs Defense properties of neutrophils & macrophages –Chemotaxis –Diapedesis –Amaeboid Motion –Phagocytosis

Blood Film

Hematopoiesis

Leucocytes (WBCs) – cont. General Characteristics & types of WBCs Types of WBC 1.Granular (polymorphnuclear): Neutrophil 62%. –10-16um, nucleus 2-5 lobes, purple cytoplasmic granules Eosinophil 2.3%. –12-18um, 2 lobes nucleus, coarse red granules Basophil.4%. –10-14um, rarely segmented nucleus, nucleus hidden by large round bluish granules

Leucocytes (WBCs) – cont. General Characteristics & types of WBCs Types of WBC 2.Agranular WBC –Monocytes 5.3% 15-20um, kidney shape nucleus –Lymphocyte 30% round nucleus –small (5-8um) –large (9-15um)

Formed Elements of Blood Red blood cells ( erythrocytes ) White blood cells ( leukocytes ) –granular leukocytes neutrophils eosinophils basophils –agranular leukocytes lymphocytes = T cells, B cells, and natural killer cells monocytes Platelets

Leucocytes (WBCs) – cont. Genesis (Production) of WBCs Pluripotential stem cell Committed Stem cell RBCs WBCs Platelets MylocyticLymphocytic Linage

Hematopoiesis

Leucocytes (WBCs) – cont. Genesis (Production) of WBCs- leucopoiesis) Sites of WBC formation Granulocytes (neutrophil, basophil, eosinophil): –bone marrow Agranulocytes –lymphocytes- bone marrow, thymus, lymphoid tissues –monocytes- bone marrow

Life Span of WBCs Granulocytes: 4 to 8 hrs (transit time ) in blood circulation 4 to 5 hrs in tissues –In infections life span a few hours Monocytes : –10 to 20 hrs in blood circulation –Leave capillaries to tissues, increase in size to become tissue macrphages which live for months

Life Span of WBCs- cont. Lymphocytes: A few hrs in blood circulation >> tissues >> lymph >>> Blood (Recirculation) ?Life span: weeks to months

Leucocytes (WBCs) General Characteristics & types of WBCs Genesis (Production) of WBCs Life Span of WBCs Defense properties of neutrophils & macrophages –Chemotaxis –Diapedesis –Amaeboid Motion –Phagocytosis

Defense properties of neutrophils & macrophages Attack and destroy bacteria, viruses Sequence of events: –Chemotaxis –Diapedesis –Amaeboid Motion –Phagocytosis

Netrophils function-cont. Defense properties of neutrophils & macrophages- cont Phyagocytosis: Engulfing and killing of bacteria or any invading organism Steps: Chemotaxis: –Bacterial & viral toxins Products of damaged tissues : attract neutrophil to accumulate at infected site. –Opsonization: plasma substances (IgG) attached to the bacteria to make them easy to phagocyte

Diapedesis

Defense properties of neutrophils & macrophages Attack and destroy bacteria, viruses Sequence of events: –Chemotaxis –Diapedesis –Amaeboid Motion –Phagocytosis

Defense properties of neutrophils & macrophages Attack and destroy bacteria, viruses Sequence of events: –Chemotaxis –Diapedesis –Amaeboid Motion –Phagocytosis

Phagocytosis- cont. Phagocytosis is selective: Distinguish self from non-self…... How? –Normal tissues have smooth surface –Normal tissues have protective protein surface –Antibodies coating bacteria ( Opsonization)

Phagocytosis

Phagocytosis by neutrophils- cont. Neutrophils attach to bacteria & encircled it with pseudopodia and take it into a vacuole (phagosome). One Neutrophil can engulf 3 to 20 bacteria One Macrophage can engulf up to 100 bacteria Microbial killing: fusion of neutrophil granules with vacuole, –Discharge of lysozyme, myeloperoxidase enzymes into the vacuole, killing and digesting the engulfed bacteria. –Release of Free radicals by oxidizing agents: superoxide, hydrogen peroxide to kill the bacteria

Leucocytes (WBCs) – cont. Types of WBC 1.Granular (polymorphnuclear): Neutrophil 62%. –10-16um, nucleus 2-5 lobes, purple cytoplasmic granules Eosinophil 2.3%. –12-18um, 2 lobes nucleus, coarse red granules Basophil.4%. –10-14um, rarely segmented nucleus, nucleus hidden by large round bluish granules

Blood Film

Eosinophils Function: Phagocytosis: Phagocytosis is same as neutrophil, but less efficient Chemotaxis: eosinophil attracted towards chronic inflammation/allergic tissue ( allergic disease of skin & lungs) By eosinophil chemotactic factor Phagocytose (& detoxify) antigen/antibody complexes

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

Leucocytes (WBCs) – cont. Types of WBC 1.Granular (polymorphnuclear): Neutrophil 62%. –10-16um, nucleus 2-5 lobes, purple cytoplasmic granules Eosinophil 2.3%. –12-18um, 2 lobes nucleus, coarse red granules Basophil.4%. –10-14um, rarely segmented nucleus, nucleus hidden by large round bluish granules

Leucocytes (WBCs) – cont. Types of WBC 1.Granular (polymorphnuclear): Neutrophil 62%. –10-16um, nucleus 2-5 lobes, purple cytoplasmic granules Eosinophil 2.3%. –12-18um, 2 lobes nucleus, coarse red granules Basophil.4%. –10-14um, rarely segmented nucleus, nucleus hidden by large round bluish granules

Blood Film

Basophils Similar to tissue mast cells Non-phagocytic cells Granules: dark blue color. Granules contain: –Heparin –Histamine –Serotonin (5HT). Released during allergic reactions

Hematopoiesis

Blood Film

Defensive Functions of the Monocytes Directly: –phygocytosis of bacteria, dead cells etc Indirectly: –Cooperates with lymphocytes by: Recognizing the foreign body Ingesting the foreign body Processing the foreign body Presenting it to lymphocytes

Monocyte-macrophage system Reticulo-endothelial System

Reticuloendothelial System- RES Blood Monocyte Tissue macrophage Attached (fixed) Mobile Function is phagocytosis of: Bacteria Viruses Dead tissues Foriegn particles Immune function

Reticuloendothelial System- RES RES is widespread in the body Cells of the RES: –Monocytes (blood macrophages) –Mobile and fixed tissue Macrophages –Specialiazed endothelial cells in bone marrow, ly mph nodes and spleen –Reticular cells of lymph nodes spleen & bone marrow.

Reticuloendothelial System- RES Cells of the RES - Distribution: Tissue Macrophages in skin SC tissues Tisssue Macrophages of lymph nodes Tissue macrophages in lungs Macrphages (kupffer cells) in the liver Macrphages in the spleen and bone marrow

Reticuloendothelial System- RES Blood Monocyte Tissue macrophage Attached (fixed) Mobile Function is phagocytosis of: Bacteria Viruses Dead tissues Foriegn particles Immune function