Innate Immunity Flashcards
What would occur in the absence of innate immunity?
The invading pathogens would grow uncontrollably and kill the host
What would happen in the absence of adaptive immunity?
Infections are initially controlled by innate immunity however the invading pathogen can not be eliminated completely
Which cells are the main defense against extracellular infection (bacteria)?
Abs and PMNs
Which cells are the main defense against intracellular infection (viruses)?
CTLS, NK cells, macrophages
Neutrophil function
Early phagocytosis and killing of microbes
NK cell function
Lysis of infected cells, activation of macrophages
Function of C-reactive protein
Opsonization of microbes and activation of complement
Function of TNF, IL-1 and chemokines
Inflammation
Function of IFN-alpha and beta
Resistance to viral infection
Local effect: inhibition of viral gene replication
Up regulate expression of MHC class I molecules
IFN-gamma function
Macrophage activation
IL-12 function
Potent inducer of IFN-gamma production by NK cells and T cells
IL-15 function
Proliferation of NK cells
IL-10 and TGF-beta function
Control of inflammation
In most cases innate immune response to pathogens
Prevents, controls or eliminates infection without engagement of adaptive immunity
Innate immunity also functions to eliminate host damaged cells and initiate the process of tissue repair that involves
Recognition of stressed, damaged and/or dead host cells, phagocytosis and clearance of cellular debris, and stimulation and control tissue remodeling
IFN-gamma/IL-12 amplification loop
Macrophages secrete IL-12 which stimulates the NK cells to produce IFN-gamma
IFN-gamma activates phagocytosis and killing of microbes by macrophages
Macrophages treated with IFN-gamma exhibit a classical activation profile that is characterized by
Increased synthesis of pro-inflammatory cytokines, increased production of ROS, synthesis of inductive NOS, up-regulation of lysosomal enzymes and enhances Ag presenting properties
Killing of a host cell by NK cells will always occur if either
MICA/MICB expression is increased or class I MHC expression is decreased
What systemic effects are produced by IL-1, TNF-alpha and IL-6?
Fever (potency: IL-1>TNF>IL-6)
Induction of acute phase proteins (IL-6>IL-1>TNF-alpha)
Arthralgia/myalgia (TNF-alpha)
Virus Ag-activated B cells produce low affinity/high avidity anti-viral IgM but B cells educated by Th2 cells differentiate and switch production of
Low affinity/high avidity anti-viral IgM to high affinity anti-viral IgG or IgA of exactly the same specificity
What are the local affects of TNF and IL-1?
Increased adhesion and permeability of blood vessels as well as activation of leukocytes
What are the systemic pathological effects of TNF?
Low CO, thrombus and increased permeability of blood vessels, insulin resistance effecting multiple tissues
When infected with coronavirus what cytokines are released by macrophages?
TNF-alpha, IL-1 beta, IL-6 and IL-18 (liver damage)
Which cytokines are involved in septic shock/sepsis associated tissue injury?
TNF-alpha, IL-1 (involved in regulation of fever)and IL-6 (regulates synthesis of acute phase proteins)
Also involved in leukocyte activation and SIRS
