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MLAB 1415- Hematology
Keri Brophy-Martinez
Chapter 7: LeukocytesPart 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 Myeloid Progenitor= CMP
Common Lymphoid progenitor= CLP
Neutrophils
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
Band
Seg
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.