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MLAB 1415- Hematology Keri Brophy-Martinez. Chapter 7: Leukocytes Part One. Terms. Myelopoiesis the production and development of myeloid cells in the bone marrow Also known as granulocytopoiesis. Leukocytes. Function Protect the host from infectious agents or pathogens
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MLAB 1415- HematologyKeri Brophy-Martinez Chapter 7: Leukocytes Part One
Terms • Myelopoiesis • the production and development of myeloid cells in the bone marrow • Also known as granulocytopoiesis
Leukocytes • Function • Protect the host from infectious agents or pathogens • Innate=Natural Immune response • 1st response to pathogens (nonself) • Always available • Neutrophils, monocytes, and macrophage main players • Adaptive Immune response • Starts in lymphoid tissue • Slow • Long-lasting immunity (memory) • Lymphocytes become “activated”
Common Lymphoid progenitor= CLP Common Myeloid Progenitor= CMP
Neutrophil Lifespan • Three areas • Bone marrow • Differentiation, proliferation, maturation • Peripheral blood • Circulate for a few hours • Tissues • Work in host defense
Regulation • Neutrophil production primarily regulated by cytokines • Interleukin-3 • Granulocyte -monocyte-colony stimulating factor (GM-CSF) • Granulocyte-colony-stimulating factor (G-CSF)
Maturation Changes • Nucleoli disappear • Chromatin condenses • Nuclear mass indents and segments • Cytoplasm becomes granular & pinkens
Seg Band
Maturation of the granulocytic series**Least mature to mature** • Myeloblast • Size: 14-20µm • Cytoplasm • Slight amount/blue • No granules (possible Auer rods to be discussed in another section) • Nucleus • Round/Central or eccentric • Reddish purple • 1-3 nucleoli • Fine meshlike/lacy chromatin with no clumping • N:C ratio = 4:1
Maturation of the granulocytic series • Promyelocyte (progranulocyte) • Size: 15-21 µm • Cytoplasm • Increased amount/blue • Fine, azurophilic, nonspecific granules present • Nucleus • Round/Central or eccentric • Reddish-purple • Fine, meshlike/lacy chromatin beginning to clump • 1-2 nucleoli • N:C ratio = 3:1
Maturation of the granulocytic series • Myelocyte • Last myeloid cell capable of division • Size: 12-18µm • Cytoplasm • Increased, bluish-pink (“dawning of neutrophilia”) • Fine specific granules • Secretory vesicles • Nucleus • Round or oval/eccentric • Reddish-purple • Chromatin loosely clumped • No nucleolus • N:C ratio = 2:1 or 1:1
Maturation of the granulocytic series • Metamyelocyte • Also called “meta” or “juvenile” • Size: 10-18µm • Cytoplasm • Moderate amount • Specific granules (neutrophilic, eosinophilic or basophilic) • Tertiary granules • Secretory vesicles • Nucleus • Indented (kidney-bean shaped) • Central or eccentric • Purple • Clumped chromatin • No nucleolus • N:C ratio = 1:1
Maturation of the granulocytic series • Band • 1st stage found in P.B • Size: 9-15µm • Cytoplasm • Moderate amount • Specific granules (see meta) • Nucleus • Elongated, narrow band (sausage) shape with uniform thickness • Central or eccentric • Clumped, coarsely granular chromatin
Maturation of the granulocytic series • Segmented neutrophil • Size: 10-16µm • Cytoplasm • Neutrophil - Granules stain equally with eosin and methylene blue, causing a pinkish appearance • Normal in circulation = 40 - 80% • Nucleus • Neutrophil - purplish-red, clumped granular chromatin, 2-5 distinct nuclear lobes connected by a filament of chromatin
Eosinophil • Eosinophil - Granules stain mainly red, due to reaction with eosin in stain • Normal in circulation = 0-5% • Eosinophil - deep blue purple, coarsely granular chromatin, 2 distinct lobes Eosinophil
Basophil • Basophil - Granules stain mainly blue, due to the reaction with methylene blue in stain • Normal in circulation = 0-1% • Mast cell is a tissue basophil • Basophil - deep blue purple, coarsely granular chromatin, 2 nuclear lobes (sometimes obscured by cytoplasmic granules Basophil
Function of the granulocytic cells • Neutrophils • Defense against bacterial infections • Eosinophils • Regulate inflammation • Respond to antigenic stimulation in chronic allergies • Interact with larval stages of some helminthic parasites • Basophils • Histamine in granules plays a role in acute, systemic allergic reactions (sudden release of histamine can cause anaphylactic shock) • Granules also contain heparin
Granulocytes: A Final Thought • Why are they called granulocytes? • The granules are lysosomes created by lipids that contain hydrolytic enzymes such as peroxidase, acid phosphatase, lysozyme and specific esterase.
References • Harmening, D. M. (2009). Clinical Hematology and Fundamentals of Hemostasis. Philadelphia: F.A Davis. • McKenzie, S. B., & Williams, J. L. (2010). Clinical Laboratory Hematology . Upper Saddle River: Pearson Education, Inc.