MLAB 1415- Hematology Keri Brophy-Martinez Leukocytes- The Granulocytes 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/Nonspecific Natural Immune response 1st response to pathogens (nonself) Always available Neutrophils, monocytes, and macrophage main players Adaptive Immune response/Specific Starts in lymphoid tissue Slow Long-lasting immunity (memory) Lymphocytes become “activated”

CMP CLP From Carr JH, Rodak BF: Clinical hematology atlas, ed 3, Philadelphia, 2009, Saunders

Neutrophils

Neutrophil Lifespan Three areas Bone marrow Peripheral blood Tissues 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 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/Stab 1st stage found in P.B Size: 9-15µm Cytoplasm Moderate amount Specific granules (see meta) Secretory vesicles 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, foreign materials Eosinophils Respond to antigenic stimulation in chronic allergies Interact with larval stages of some helminthic parasites Regulate immune response 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. Rodak, B. (2012). Hematology: Clinical principles and applications (4th ed.). St. Louis, Mo.: Elsevier Saunders.