White Blood Cells Prepared by Dr. Hamad ALAssaf Alassaf_h@yahoo.com 2015

Leukocytes / White Blood Cells Granulocytes (65%) - neutrophils, eosinophils, basophils - formed in bone marrow Monocytes (5%) - tissue macrophages Lymphocytes (30%) - formed in lymph tissue - life span: hours to years

Leukocytes Classification Granulocytes Non- Granulocytes Neutrophils - Monocytes Eosinophils - Lymphocytes Basophils Polymorphonuclear Mononuclear Phagocytes Non-phagocytes Neutrophils, monocytes - Lymphocytes Macrophages, eosinophils - Basophils Granulocytes granules in cells Polymorphnuclear Multilobed nucleus Phagocytes

Phagocytic Cells 2- Monocytes/Macrophages 1- Polymorphonuclear Neutrophils - non-dividing, short-lived (6 hours to a few days) - dominant number in bloodstream 2- Monocytes/Macrophages - long-lived cells (months) - do not circulate - present in tissue, particularly in lungs, spleen, liver, lymph nodes - tissue macrophage system Neutrophils 9-10 days 5-7 days in maturation and storage, 2-3 days in bone marrow

Actions of Phagocytic Cells 1. Margination 2. Diapedesis 3. Ameboid Motion 4. Chemotaxis 5. Phagocytosis

Actions of Phagocytic Cells

Phagocytosis 2. Engulfment 1. Binding 3. Phagosome formation Acidification proteolysis MHC II 4. Lysosome fusion 6-Antigen presentation 5 Membrane disruption

Cell-mediated Response to Inflammation 1. Tissue macrophages: - already present in tissue 2. Neutrophil invasion: - margination, diapedesis, chemotaxis - stimulation of bone marrow to release stored leukocytes, 4-5 hours 3. Macrophage proliferation: - invasion by circulating monocytes (several hours to increase size) 4. Stimulation of granulocyte and monocyte production: - growth factors produced by tissue macrophages (TNF, IL-1, Cell stimulating factor)

NORMAL PRODUCTION INFECTION Marrow pool Increased Production Production Decreased marrow pool Bone Bone Increased circulation Increased margination Circulating and marginated pools Blood vessel Blood vessel Increased Transmigration Transmigration Tissue Tissue Site of inflammation

Granulocytes ~ 0.5% of total white blood cells EOSINOPHILS: BASOPHILS: - active against parasites, skin diseases, chronic infections - phagocytic and immunomodulatory, decrease inflammation - life span 5 days BASOPHILS: ~ 0.5% of total white blood cells - basophils similar to mast cells - release primarily histamine, some bradykinin - release due to binding of IgE - Life span a few hours to a few days

Important terms Leukopenia : decrease in the number of white blood cells. example: bone marrow suppression Leukocytosis : increase in the number of white blood cells. example : bacterial infections Leukemia : (cancerous) uncontrolled production of white blood cells

Neutropenia Neutropenia: decreased number of neutrophils due to: Decreased production Increased neutrophil destruction (chronic infections) Agranulocytosis: severe neutropenia due to: production failure due to irradiation exposure to chemicals drugs Decrease production inherited stem cell disorders chemical toxicity Increased destruction infections, immune mechanisms

Immunity It is a special defense mechanism which is mobilized when the body is invaded by a foreign organism.

Immunity Innate = (present since birth) - ability to resist damaging organisms and toxins - skin, gastric acids, tissue neutrophils and macrophages, complement Acquired = (developed by exposure to specific invading agents). - humoral ----> circulating antibodies - cellular ----> activated cells

Sequence - Dormant lymphocytes - Invasion of body by foreign antigen - Phagocytosis by macrophages - Presentation of antigen to lymphocytes 2 x1012 lymphocytes

Antigen An antigen: is a substance that can induce an immune response when introduced into an immunocompetent host and that can react with the antibody produced from that response. Macromolecule Protein polysaccharide Most antigens have variety of antigenic determinants

Lymphocytes T- and B-Cells T8-supressor Pre-T Cell T-Cell Thymus T4-helper Bone Marrow Stem cell Pre-B Cell B-Cell Plasma Cell Liver and Bone marrow IgG IgA IgM IgD IgE

T-cells Cytotoxic Cells Helper Cells ( CD-4 cells) Suppressor Cells kill infected cells Helper Cells ( CD-4 cells) activate macrophages and B-cells Suppressor Cells regulate activity