Innate immunity

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  • Created by: SamDavies
  • Created on: 04-05-19 23:29
What two things initiate acute inflammation?
Breakage of tight junctions and release of DAMPs
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Which components are specific to bacteria and so are recognised as foreign by the body?
Lipopolysaccharide (LPS) and peptidoglycan
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Which innate immune cells are known as phagocytes?
Macrophages, neutrophils and dendritic cells
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Which innate immune cells are known as granulocytes?
Neutrophils, mast cells, basophils, eosinophils
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Which innate cells are sentinel cells (found in tissue)?
Macrophages, mast cells and dendritic cells
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Which innate cells are effector cells (found in blood)?
Neutrophils, basophils, eosinophils, monocytes, NK cells
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Activation of mast cells causes what?
Degranulation; the release of histamine and vasodilation. This makes the blood vessels leaky and allows effector cells to migrate to the site of infection. It can also lead to swelling
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What happens when neutrophils migrate to the site of inflammation?
They bind to the pathogen/antigen, which has already received co-stimulation by the binding of antibody and complement to the pathogen. This causes phagocytosis and a respiratory burst kills it
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What happens to the neutrophils after they phagocytose the pathogen?
Macrophages phagocytose the neutrophils. If there are too many neutrophils to be phagocytosed, the excess forms pus
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What does G-CSF do?
Growth factor for neutrophils. If there are too few neutrophils (e.g. because of chemotherapy), it can lead to neutropenic sepsis. G-CSF mobilises cells from the bone marrow so it causes bone pain
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What do the humoral components of the innate immune system do?
Substance P causes pain. Histamine/bradykinin/NO release causes vasodilation and leaky blood vessels which can result in swelling and redness. The release of cytokines like IL-1 and IL-6 causes pyrexia
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What happens to activated macrophages?
Release of cytokines (IL-1, IL-6, TNF-alpha). Some go to the liver and produce CRP, some go to the hypothalamus and cause pyrexia. Macrophages also release PGs and leukotrienes which prolong vasodilation + oedema so longer inflammatory response
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What does the classical pathway of complement activation involve?
Antibodies bind to pathogens, resulting in activation of C3
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What does the MBL pathway of complement activation involve?
CRP and MBL bind directly to the pathogen, resulting in activation of C3
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What does the alternative pathway of complement activation involve?
Spontaneous activation of C3b which also binds to the pathogen
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What does C3b do?
Binds to surface of pathogen and flags it to the immune system (opsonisation/tagging)
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What does C3a do?
Acts as a chemoattractant and facilitates the degranulation of mast cells to release histamine
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What does C5b do?
Forms a membrane attack complex with other complement molecules. This complex buries holes in the pathogen cell wall and causes it to lyse.
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What does C5a do?
A chemoattractant - efficient at causing neutrophil chemotaxis
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What do congenital and acquired complement deficiencies cause?
Membrane attack complex can't assemble properly which increases susceptibility to meningococcal meningitis. Deficiencies can be counteracted through vaccinations and prophylactic antibiotics
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What are a few ways cytokines and cytokine action can be inhibited?
Monoclonal antibodies can be designed to inhibit the cytokine or its receptor; a soluble receptor can bind to cytokine; a mimic of a receptor antagonist can be produced; inhibitors of signalling molecules can be produced
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What is an anti-TNF alpha drug and why is it used?
TNF-alpha worsens rheumatoid arthritis by causing inflammation, eroding bone, destroying cartilage and producing pain. Infliximab inhibits TNF-alpha. Anti-TNF alpha can cause latent TB to become active - pts should be screened
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Other cards in this set

Card 2

Front

Which components are specific to bacteria and so are recognised as foreign by the body?

Back

Lipopolysaccharide (LPS) and peptidoglycan

Card 3

Front

Which innate immune cells are known as phagocytes?

Back

Preview of the front of card 3

Card 4

Front

Which innate immune cells are known as granulocytes?

Back

Preview of the front of card 4

Card 5

Front

Which innate cells are sentinel cells (found in tissue)?

Back

Preview of the front of card 5
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