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Medicine Haematology Summary
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3rd year haematology summary of lecture notes
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Haematology BlockSection 3 Summary
Chaandanee Bhayroo
1420214
GEMP 1
,Leucocytes
● Function = defence against infections
Innate Immune System:
● Granulocytes
o Neutrophils
o Eosinophils
o Basophils
● Monocytes
● Natural Killer Cells
Adaptive Immune System:
● B lymphocytes
● T lymphocytes
Neutrophils
● Seek and destroy
Life Cycle
1. Produced in the bone marrow and only once
matured will the leave and enter the peripheral
blood system
2. Some travel in the blood stream
3. Others surveillance the endothelium =
inflammation and cytokines attract them
4. Enter the tissues and kills BACTERIA by either
phagocytosis / NETosis
5. Also secrete chemokines to recruit other cells to
the site of inflammation
Controls of neutrophil activity
Extensive network of receptors for:
● Opsonins – immunoglobulins, complement
● Chemotaxins – recruitment
● Growth factors – enhance stimulation
● Other inflammatory mediators – recognise damage
Moving from the blood to the tissues
1. Rolling of neutrophil by selectins on both
neutrophil and quiescent endothelium
2. Activated endothelium allows ICAMs to
bind to integrins on neutrophil =
activating neutrophil (nucleus elongates)
3. Transmigration and follows chemotactic
gradient
,Neutrophil form and function
● If proteins and pathways are activated all the time, the cell would not survive for very long
(self-digestion)
● Thus, it is packaged in granules
Granules
● Primary: formed in the promyelocyte
● Secondary/specific and tertiary: formed in the myelocyte and metamyelocyte
Antimicrobial Mechanisms:
● Can generate oxygen and nitrogen dependent molecules = oxidises infectious material (kills)
● Very complex cells
Neutrophil Extracellular Traps (NETs)
● Neutrophils extrude sticky fibres
(chromatin) onto the bacteria and
granules rupture causing bacteria
to die
● Strands of chromatin physically
trapping the bacteria
● Pus = sticky and viscous = due to
chromatin fibres
● May be of different colours = due to
bacteria or breakdown of RBCs or
enzymes of primary granules
Intracellular Killing
● Some of the enzymes required to phagocytize come
from the membrane, produced in granules,
proteases, lysosomes & are only brought together
when neutrophil phagocytoses a bacterium
, Side Effect of Neutrophil Function:
= Tissue Destruction if excessive and not kept in check
Neutrophil Pools
1. Mature neutrophils in the marrow (reserve pool)
2. Circulating neutrophils (24hrs):
- marginating
- free flowing (FBC)
3. Sequestered in the spleen (can contract and release at time of need)
4. In the tissues
Neutrophil Disorders
Qualitative:
● Inherited
● Acquired
Quantitative:
● Increased
● Decreased
Neutrophilia
● Increased synthesis
● Mobilisation of unmeasured pools (does not mean increased production)
Neutropenia
● Decreased synthesis
● Increased destruction/ sequestration
Eosinophils
● Very complex cells
● Part of the Th2 response
● Production is Il-5 dependent
● Homing to the tissues, principally the gut/ lungs, is mediated by eotaxin (chemotaxin)
● Many are lost by moving into the lumen of the gut
Life Cycle
1. Circulate for about 18 hours
2. Most go to the gut. Emigration into the tissues is initiated by selectin/ligand pairing on the
endothelium (very specific interaction)
3. Thought to be quite long-lived in the tissues with most loss occurring by migration into the
gut or alveolar lumen.
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