LEUKOCYTE DEVELOPMENT, KINETICS, AND FUNCTIONS Flashcards
• Relatively colorless compared to red blood cells.
LEUKOCYTES (WBC)
• CLASSIFIED ACCORDING TO:
• Granularity
• Nuclear Segmentation
• Function
Function of WBCs
mediating immunity
• 3 Body Compartments
Bone Marrow
Peripheral Blood
Tissues
• TYPICAL REFERENCE INTERVAL:
4.5 X 10^9/L - 11.5 x 10^9/L
WBCs with granules and different staining characteristics
GRANULOCYTES
• - granules containing basic proteins
• - granules that are acidic
• - granules that react with both acid and basic stains
EOSINOPHIL
BASOPHIL
NEUTROPHILS
MONONUCLEAR CELLS
• Categorized into (2)
monocytes and lymphocytes
• Cells have nuclei that are not segmented
Mononuclear cells
NEUTROPHIL: DEVELOPMENT
• Occurs in the______
• __________
• Share common progenitor with monocytes
• Distinct from eosinophil and basophil
bone marrow
GRANULOCYTE MONOCYTE PROGENITOR (GMP)
3 POOLS OF DEVELOPING NEUTROPHILS IN THE BM
Stem cell pool
Proliferation (mitotic) pool
Maturation (storage) pool
Stem cell pool
Proliferation pool
Maturation pool
HSC
CMP
GMP
Myeloblast
Promyelocyte
Myelocyte
Metamyelocyte
Band
Neutrophil
Neutrophil
• Earliest morphologically identifiable granulocyte precursor
MYELOBLAST
Neutrophil
• Thin rim of basophilic cytoplasm
• No granules
• Lacy chromatin pattern
• Two or more nucleoi
MYELOBLAST
MYELOBLAST
• High N:C ratio (____)
•_____ um
•_____ in the normal bone marrow
• NOT FOUND IN PERIPHERAL BLOOD
6:1
14-20um
0-3%
MYELOBLAST
• Fine nuclear chromatin and slightly basiphilic cytoplasm
• 2-4 visible nucleoli
• Have NO VISIBLE GRANULES
TYPE I MYELOBLAST
MYELOBLAST
• Presence of less than twenty primary granules in the Cytoplasm
TYPE II MYELOBLAST
MYELOBLAST
• Darker chromatin and more purple cytoplasm
• More than twenty granules in the cytoplasm
TYPE III MYELOBLAST
PROMYELOCYTE
• Comprise____ of the nucleated cells in the BM
•____ um in dm
1-5%
16-25
• NUCLEUS: round to oval and is often eccentric
• Paranuclear halo or “hof” = seen in normal but not in malignant cells
• Chromatin clumping maybe visible
• 1-3 nucleoli can be seen but maybe obscurec by the granules
PROMYELOCYTE
• CYTOPLASM: basophilic and full of primary (azurophilic) granules
• 1st in a series of granules to be produced
• NOT SEEN IN PERIPHERAL BLOOD
PROMYELOCYTE
• Make up 6-17% of the nucleated cells in the BM
• FINAL STAGE OF MITOSIS OCCURS
• Primary granules => ceases
• Secondary granules(specific) => begins to manufacture
MYELOCYTE
Divided to 2 myelocyte
•_______ - look similar to promyelocytes
• Patches of grainy pale pink cytoplasm
• SECONDARY GRANULES begin to be evident “DAWN OF NEUTROPHILIA”
• _______- smaller the promyelocyte (15-18 um)
• NUCLEUS: more heterochromatin
• Nucleoli: difficult to see
Early myelocyte
Late myelocyte
• Constitute 3-20% of nucleated marrow cells
• NO LONGER CAPABLE OF DIVISION
• SIZE: 14-16 um
• NUCLEUS: indented
• Chromatin - increasingly clumped
• Nucleoli - Absent
• TERTIARY GRANULES - begin during this stage
METAMYELOCYTE
• CYTOPLASM: contains very little residual RNA
• Little to no basophilia
• SEEN IN PERIPHERAL BLOOD OF NEWBORNS
METAMYELOCYTE
• Make up 9-32% of nucleated marrow cells
• 0-5% of the nucleated peripheral blood cells
• Pale - blue pink cytoplasm
• RNA is absent
• Curved, band-shaped nucleus which has not developed a threadlike filaments
• TERTIARY GRANULES: continue to be formed
BAND CELL or STAB CELL
• SECRETORY GRANULES
(aka: secretory vesicles) - begin to form
• Greatest source of variation and discrepancy in leukocyte morphology
BAND CELL or STAB CELL
MATURE NEUTROPHIL
•_________ granules
• Course, clumped chromatin
•_____ lobes
•_____ um
Pink to rose-violet specific
3-5
9-15
MATURE NEUTROPHIL
• LIFESPAN:____
•_____ in the bone marrow
• IN THE PERIPHERAL BLOOD
•_____(Relative Count)
•________ (absolute count)
9-10 days
7-30%
50-70%
2.3-8.1x10^9/L
KINETICS
• BONE MARROW
• Transit time from HSC to myeloblast
• Not measured
• Transit time from myeloblast to myelocyte
•_____
• Transit time through maturation pool
•______
6 days
4-6 days
NEUTROPHIL KINETICS
• BLOOD
•_________
• Freely floating in the bloodstream
•__________
• Adhering to the blood vessel wall
• Stays for____ hours in the blood
• TISSUE
• Dies after doing its function
CIRCULATING NEUTROPHIL POOL
MARGINAL NEUTROPHIL POOL
7
NEUTROPHIL KINETICS
• EXTRAVASATION
• ROLLING
• ADHESION
• CRAWLING
• TRANSMIGRATION
NEUTROPHIL GRANULES
PRIMARY
SECONDARY
TERTIARY
PRIMARY GRANULES
Myeloperoxidase
Elastase
Proteinase-3
Cathepsin G
Defensins
SECONDARY GRANULES
Collagenase
Lactoferrin
NADPH oxidase
TERTIARY GRANULES
Gelatinase
Plasminogen activator
Acid hydrolase
NEUTROPHIL FUNCTIONS
• INNATE IMMUNE SYSTEM
• PHAGOCYTOSIS (4)
• Recognition and Attachment
• Ingestion
• Oxygen-Dependent Killing
• Oxygen Independent Killing
FUNCTIONS
• INNATE IMMUNE SYSTEN
• PHAGOCYTOSIS
• Phagocyte receptors bind to
certain foreign molecular patterns and opsonins such as antibodies
and complement components
• Pseudopodia formation to engulf the pathogen
• Respiratory burst through production of H202 (primary ROS) and hypochlorite (secondary ROS)
• Other enzymes
• Recognition and Attachment
• Ingestion
• Oxygen-Dependent Killing
• Oxygen Independent Killing
NET
NEUTROPHIL EXTRACELLULAR TRAPS
EOSINOPHIL
• EOSINOPHIL DEVELOPMENT
Cytokines
• IL-3,IL-5 and GM-CSF
• TF(GATA-1, PU.1 and c/EBP)
• GATA-1 and PU.1=MBP
EOSINOPHIL
_______
• Microscopically the same as neutrophil
•_______
• Microscopically the same as neutrophil promyelocyte but cytochemically different because of CHARCOT-LEYDEN CRYSTAL PROTEIN
MYELOBLAST
PROMYELOCYTE
EOSINOPHIL
•_______
• Same nuclear characteristics
with neutrophil myelocyte but contains large, pale, reddish-orange secondary granules
•________
• Secondary granules increase in number
• Secretory vesicles appear
• Lipid bodies and small granules appear
MYELOCYTE
METAMYELOCYTE AND BANDS
EOSINOPHIL
• Make up 1-3% of nucleated cells in the bone marrow and peripheral blood
• Usually with BILOBED NUCLEUS
• Cytoplasm contains refractile,
orange-red secondary granules
• MATURE EOSINOPHIL
EOSINOPHIL KINETICS
• Transit time from last myelocytic division to release of mature eosinophils is______
• HALF LIFE:____ in the circulation
• Survival in tissue:____
• Tissue destination:
• Columnar epithelial surface in the respiratory, gastrointestinal and genitourinary tract
3.5 days
18 hours
2-5 days
EOSINOPHIL FUNCTION
• EOSINOPHIL DEGRANULATION
• CLASSICAL EXOCYTOSIS
• COMPOUND EXOCYTOSIS
• PIECEMEAL DEGRANULATION
• CYTOLYSIS
EOSINOPHIL FUNCTION
• EOSINOPHIL DEGRANULATION
• Granules fuse with plasma membrane
• Granules fuse with each other then with the plasma membrane
• Secretory vesicles remove specific protein from granules then fuse with plasma membrane
• Eosinophil sombrero vesicles
• Spilling of cellular contents
• Second most common observed mode of degranulation
• CLASSICAL EXOCYTOSIS
• COMPOUND EXOCYTOSIS
• PIECEMEAL DEGRANULATION
• CYTOLYSIS
EOSINOPHIL FUNCTIONS
• Pleiotropic Multifunctional Leukocyte
• Allergy
• Immune regulation
• Adaptive Immunity
• Acute and Chronic Allograft Rejection
• Poor phagocytes
• Plasma Cell Survival
• Viral Infections
• Platelet-eosinophil interaction
EOSINOPHIL FUNCTION
• IgE response is physiological
response to helminth infection
• IgE axis evolved to counter metazoan parasites (worms and parasitic arthropods) which are too large to be phagocytosed
• Allergy is misdirected anti-parasite response in hypersensitive people
• PARASITE KILLING
GRANULOCYTES
BASOPHIL
• BASOPHIL DEVELOPMENT
Cytokines??
• Staging is not done
• IL-3, TSLP
• IgE dependent (IL-3)
• Non-IgE dependent (TSLP)
• Round to lobulated nuclei
• Slightly condensed chromatin
• Cytoplasm is blue and contains large blue-black secondary granules
• IMMATURE BASOPHIL
• Lobulated nucleus often obscured by granules
• Clumped chromatin
• Colorless cytoplasm with large blue-balck granules
• Granules are water soluble
MATURE BASOPHIL
BASOPHIL
KINETICS
• POORLY understood of their rarity in the bone marrow and circulation
• LIFE SPAN:_____
• IL 3 and 25 are anti-apoptotic
60 hours
Basophil Granules
Secondary Granules
Histamine
Platelet-activating factor
Leukotriene Ca
Interleukin-4
Interleukin-13
Vascular endothelial growth factor A
Vascular endothelial growth factor B
Heparan sulfate
FUNCTION
• ALLERGY
• Initiator of allergy
• Adaptive Immunity
• antigen presentation
BASOPHIL
• Poor Phagocytes
• Angiogenesis
• Helminthic Infection
• Lymphocyte-mediated
delayed hypersensitivity
BASOPHIL
GRANULOCYTES
• Kit-Ligand
• Microscopically similar to basophil
(but bigger)
• Progenitors originate in the bone marrow and spleen
• Has longer life span than basophil
MAST CELLS
Granulocyte
Contains protease, peptidoglycan and cytokines in its granules
MAST CELL
MAST CELL
FUNCTION
• Allergy
• Inflammation
• Antigen presentation
• Anti-inflammatory
• Immunosuppression
• Immunologic gatekeepers
