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3 IIH > 5.2 Neutrophils > Flashcards

5.2 Neutrophils Flashcards

1
Q

What proportion of leukocytes are neutrophils?

A

60-70%

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2
Q

What is the half life of neutrophils?

A

8-12 hours

spontaneous apoptosis

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3
Q

How are neutrophils activated?

A

inflamed / infected tissues release inflammatory cytokines

neutrophil interacts with endothelium (maybe selectins)

neutrophils rolls and tethers

firm adhesion forms

extravasation

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4
Q

What is extravasation?

A

neutrophils squeezes into tissues surrounding the endothelium, where it was attracted to by the cytokine gradient

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5
Q

What signal might be used to stop neutrophils at their migratory endpoint?

A

fMLP

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6
Q

What signals might be used to alter the direction of neutrophils?

A

IL-8

LTB4

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7
Q

What receptors act as neutrophil recognition sites?

A

PAMPS (pathogen associated molecule pattern molecules)
DAMPS (damage associated molceule pattern molecule)s
these cause gene expression, and neutrophils can do phagocytosis

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8
Q

what do neutrohpil granules contain?

A

proteases
anti-bacterial proteins (lactoferrin)
superoxide anions (bleach)

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9
Q

What 3 states do neutrophils exist in?

A

quiescence
primed
activated

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10
Q

What are the features of the quiescent neutrophil?

A

rounded

no mobilisation of granules

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11
Q

What are the features of the primed neutrophil?

A

cytoskeletal mobilisation
(polarised bullet shape)
able to amount a fast response tenfold larger than in non-primed activated cells

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12
Q

What are the features of the activated neutrophil?

A

chemotaxis
degranulation
ROS release

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13
Q

What are ROS?

A

reactive oxygen species are chemically reactive molecules containing oxygen

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14
Q

What effects does ROS have on cells?

A

damages DNA
oxidations of polunsatured fatty acids and amino acids
deactivate specific enzymes

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15
Q

What is required for ROS to kill microbes?

A

proteinases

ideally a low-pH to optimise conditions for the anti-bacterial proteinases

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16
Q

What is the significance of Neutrophil NETs?

A

neutrophil granule contents can work outside the cell, during the late inflammation stages

though to occur whne the cell has reached phagocytic capacity

the cell extrudes unravelled DNA coated in bactericidal proteins

17
Q

What stimulates inflammation resolution?

A

Il-10, for example

18
Q

What 2 processes ocurr in inflammation resolution?

A

retrograde chemotaxis

efferocytosis

19
Q

What is efferocytosis?

A

when neutrophils are phagocytosed by macrophage

20
Q

Why do we get pus?

A

too many neutrophils for the macrophage to clear

21
Q

What happens to pus when we have too few neutrophils?

A

we don’t really get pus

22
Q

What is leukocyte adhesion deficiency?

A

we make enough leukocytes, but just don’t go where we need them, causing Omphalitis sometimes

23
Q

what is omphalitis?

A

inflammation without pus of the belly button

24
Q

How might neutrophil function be impaired?

A

failure of migration (leakocyte adhesion deficiency (defect integrins)
failure of superoxide (chronic granulomatous disease)
failure of granules (MPO deficiency, Chediak HIgashi)

25
Q

What happens in severe neutropenia?

A

neutropenic sepsis rsk is high, this is really serious

26
Q

What might cause neutropenia?

A

decreased production in the bone marrow
increased destruction
marginalisation and sequestration

27
Q

How might neutrophil production be decreased?

A

aplastic anaemia
cancers (blood)
hereditary disorders (congenital neutropenia, cyclic neutropenia)
radiation

28
Q

How might increased detruction cause neutropenia?

A

autoimmune neutropenia

chemotherapy

29
Q

How might marginilasing and sequestration cause neutropenia?

A

haemodialysis

hypersplenism

30
Q

In what circumstance might an apparently sever neutropenic patient be infact normal?

A

benign ethnic neutropenia

25-50% of african descendants and some middle easterns

31
Q

How might neutropenia be associated with many chronic diseases?

A

immunesenescene - the role of ageing in neutropenia

32
Q

What is alpha 1 anti-trypsin?

A

inhibitory protein that controls neutrophil elastase

33
Q

What happens in alpha 1 antritrypsin deficiency?

A

unopposed neutrophil action, resulting in emphysema

34
Q

What is chronic granulatous disease?

A

railure ot produce ROS - or an oxidative burst

usually X-linked
pre-atibiotics most died before age of 5
granuloma forms in tissues
recurrent and severe infections

3 IIH (23 decks)

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