Cellular Effector Mechanisms in Innate Immunity Flashcards
What is the role of resident tissue macrophages?
Immediate response during inflammation and respond rapidly to infection
Phagocytize microbes and release cytokines/chemokines
What are pattern recognition receptors (PRR)?
Expressed by all immune cells and many types of non-immune cells
Bind to foreign components (PAMP)
E.g. Toll like receptors
What is a pathogen associated molecular pattern (PAMP)?
Found on pathogens, these are molecules not found on eukaryotic cells
What is a damage associated molecular pattern (DAMP)?
Cellular components released from dead host cells
What occurs when a PRR or TLR binds to a particular PAMP?
One or all of the following:
Phagocytosis
Cytokine release
Inflammation
Activation of T cells
What is MyD88?
Common signaling pathway for inflammatory cytokines
What is the significance of the location of PAMP detection?
At surface, results in phagocytosis
If in an endosome, that signals an intracellular pathogen which could trigger the development of an adaptive immune response
What are three general consequences of TLR (all PRRs) to innate and adaptive immunity?
Secretion of cytokines by macrophages and dendritic cells
Improve phagocytosis
Enhanced ability of dendritic cells to induce adaptive immunity
What is the difference between necrosis and apoptosis?
Necrosis is the premature death of cells in living tissue by autolysis - almost always detrimental
Apoptosis is programmed cell death and is beneficial
What is the result of necrotic tissue injury?
Releases cellular factors that bind to PRRs and induce the acute inflammatory response
DAMPs act as endogenous danger signals
How do neutrophils respond to inflammation?
Marginate along blood vessel wall, followed by adhering to a specific site
The they pass through gaps in endothelial cells and migrate to the inflammatory site
What mediates the immediate innate response associated with viral infection?
Type I interferons and NK cells
What are the paracrine and autocrine functions of interferons?
Paracrine - inhibits viral binding to neighboring cells
Autocrine - causes IRF response to prevent viral replication
What three things are a part of the interferon response?
Induce resistance to viral replication in all cells
Increase expression of ligands for receptors on NK cells
Activate NK cells to kill virus-infected cells
How do macrophages and NK cells cooperate during an immune response?
Macrophages induce NK cells to proliferate (via IL-12 and IL-15)
NK cells release IFN-y which causes macrophages to increase their phagocytic activity and cytokine release
