Innate immunity II
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Innate immune response
Inflammation and cell recruitment
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Stimulation of adaptive immunity
Phagocytosis
Phagocytosis represents an early and crucial event in triggering host
defenses against invading pathogens.
Phagocytosis comprises a series of events
microbicidal function of immune cells.
antigen
presentation, allowing the induction of acquired immunity.
defense mechanism
inflammatory mediators and inflammatory cells recruitment.
Acute innate cytokines
(vasoconstriction →vasodilation)
redness, increased heat, swelling, pain, loss of function
Increase in vascular permeability
Extravasation of leukocytes
Phagocytosis
Outcome of inflammatory response
Leukocyte recruitment cascade
:Interactions of various cytokines
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IL-6, interleukin-6
Acute phase proteins:
LBP, LPS-binding protein
CRP, C-reactive protein
SAA, serum amyloid
Cytokines and their functions
:Pro-inflammatory vs Anti-inflammatory cytokines
Acute phase proteins (APPs)
specific response
systemic reaction
These proteins are secreted mainly by hepatocytes.
IL-6, TNF, and IFN-γ, are
produced by macrophages, monocytes, and other cells.
IL-6 is the
major inducer of APP.
APPs: C-reactive protein (CRP)
C-reactive protein (CRP) is a non-specific APP that binds to phosphocholine
on microorganisms.
enhancing phagocytosis
of macrophages and helping in complement binding of damaged cells.
increased rapidly within 2 hours of acute insult, rise above
normal limits within 6 hours, and peak at 48 hours.
Chronic inflammation
Granulomatous inflammation
Anti-viral immunity
pDCs detect RNA and DNA viruses with two endosomal sensors, TLR7 and TLR9,
Cellular sources of IFN-I vary with the type of viral infection.
pDCs are bone marrow-derived cells that secrete large amounts of IFN-I
(primary source of IFN-I for antiviral responses).
Cellular sources of IFN-I during virus infections
Virus
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Molecular sensors involved in virus recognition
IFN-I signaling pathway.
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Effects of IFN-I on cells during virus infections
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T-cell stimulation and T helper 1 (TH1)/TH2-cell
polarization require three dendritic cell-derived signals
Th1 response
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Th2 response
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Professional antigen presenting cells (APCs)
Summary