Module 2: Normal Leukocytes (Neutrophils) Flashcards
neutropenia
low neutrophil count
neutrophilia
increased neutrophil count
>70%
often seen in acute bacterial infections
Normal rel% of neutrophils
50-70%
Neutrophil life span
shortest of leukocytes
In bone marrow: 7-10 days
in blood: 10 hours
in tissue: 3-5 days
Maturation series of neutrophil (6)
myeloblast promyelocyte myelocyte metamyelocyte band segmented neutrophil
Myeloblast characteristics
in PBS 0
# in BM 0-2%
15-20um
NC ratio 7:1 - 5:1
Nucleus: round/oval, central, light reddish-blue, fine chromatin, no clumping, 1-3 nucleoli
Cytoplasm: Basophilic blue, scant amount, no granules
Promyelocyte characteristics
in PBS 1
# in BM 2-4%
12-24um
NC ratio 5:1 - 3:1
Nucleus: round/oval, central, light reddish-blue, fine chromatin, slight clumping at nuclear membrane, 1-2 nucleoli
Cytoplasm: basophilic (more than blast), azurophilic and nonspecific granules present
Myelocyte characteristics
in PBS 0
# in BM 5-20%
10-18um
NC ratio 2:1 - 1:1
Nucleus: oval/round, may have on side indented, usually eccentric, reddish-blue, fine chromatin with slight clumping/granular pattern, 0-2 nucleoli
Cytoplasm: bluish-pink, moderate amount, azurophilic and specific granules present
Metamyelocyte characteristics
in PBS 0
# in BM 5-15%
10-18um
NC ratio 1:1
Nucleus: indented, kidney shaped, central, light blue-purple with basophilic blue chromatin (clumped), 0 nucleoli
Cytoplasm: clear pink, moderate amount, specific neutrophilic granules present
Band characteristics
in PBS 2-6%
# in BM 10-35%
10-16um
NC ratio 1:1 - 1:2
Nucleus: elongated, horseshoe shaped, central, purplish-red, clumped chromatin, 0 nucleoli
Cytoplasm: pink, abundant, fine violet-pink neutrophilic granules present
Segmented neutrophil characteristics
in PBS 50-70%
# in BM 5-15%
10-16um
NC ratio 1:3
Nucleus: 2-5 distinct lobes, central, purplish-red, clumped chromatin, 0 nucleoli
Cytoplasm: Pink, abundant, fine violet-pink neutrophilic granules present
at what stage are neutrophils differentiated from other granulocyte cells
myelocyte stage by specific neutrophilic lysosomal granules
2 types of granules in neutrophils
primary lysosomes and azurophilic (produced beginning at promyelocyte stage)
Secondary lysosomes or neutrophilic (produced beginning at myelocyte stage)
primary (azurophilic/nonspecific) granules (4)
lysozyme
myeloperoxidase
acid phosphatase
elastase
Secondary (specific) granules (4)
Lysozyme
NADPH oxidase
Cytochrome b
Lactoferrin
Third type of granule (tertiary)
found using electron microscope
Contain plasminogen activator, alkaline phosphatase and gelatinase
Neutrophil membrane
receptors: Fc portion of IgG and C3b and C5a
Generous coating of glycoprotein on membrane surface for adherence
High concentrations of cytoskeletal proteins (actin, myosin, tubulin) essential for migration and phagocytosis
Neutrophil function
to locate and destroy pathogenic microorganisms by phagocytosis
marginating
half of neutrophils are slowly rolling along the endothelium (inside walls of blood vessels)
other half are in circulation
Average time in blood before moving to tissue
8-10hrs
**ONE WAY, cannot move back into vessels
Migration sequence (3)
1) margination, adherence, anchoring (cell flattens along endothelium)
2) diapedesis (neuts move through junctions in endothelium in response to chemotaxins from site of inflammation)
3) migration (direct or random, other neuts follow)
chemical factor signalling neut activation from bacteria
N-formyl oligopeptides
chemical factor signalling neut activation from complement
C5a, C3b, C3bi factors
chemical factor signalling neut activation from monocytes
IL-8
chemical factor signalling neut activation from membrane phospholipid (MOST CHEMOTACTIC)
Leukotriene B
chemical factor signalling neut activation from endothelium
platelet activating factor
how the neutrophil receives chemotactic substance
surface membrane has receptors
bind to chemotaxin and extend membrane at site of binding
cell extends a pseudopod
Killing cascade (5)
1) immune adherence (recognition)
2) endocytosis (englufment)
3) lysosome fusion (granule attaches to wall of phagosome and empty contents into vacuole)
4) Killing and digestion
5) exocytosis
Respiratory burst
stimulated from endocytosis
increased glycolysis from pathways produce energy/co-enzymes for oxygen dependent killing reaction
NADPH oxidase from phagosome is activated and causes reduced oxygen to superoxide
Eventually produces HOCl which is highly effective at killing phagosome
AKA peroxide/peroxidase/halide system
other killing mechanisms
acid pH kills pneumococcus
microbicidal enzymes (lysozyme-arginase, primary glucoxidase, lactoferrin)
H+ ions in granular proteins kill E. coli
Lysozyme hydrolyzes the mucopolysaccharide walls of some bacteria
diapedesis
when neutrophil changes shape to move from blood vessel to tissue
maturation series summary
in PBS increases
# in bone marrow increases (until band cell @35%) then decreases
Size: myeloblast to promyelocyte - gets larger
All cells after that get smaller
Overall size from 15-20um to 10-16um
NC ratio Decreases until metamyelocyte (1:1) then increases until seg neutrophil (1:3)
Nucleus: from round, light reddish-blue with fine chromatin and no clumping to lobed, fully clumped, purplish-red
1-3 nucleoli to 0 nucleoli
Cytoplasm basophilic blue with no granules (myeloblast) to azurophilic and specific granules present (myelocyte) to neutrophilic granules only (seg neut)
