Defenses and Deficiencies Part 2 Flashcards
What do immune cells use to identify and destroy a pathogen?
They use pathogen associated molecular patterns (PAMPs); On pathogen cell surfaces.
Which cells have Pattern Recognition Receptors?
Immune cells, phagocytic, epithelial, hepatocytes, and leukocytes.
Where are PAMP (Pattern recognition) receptors?
Located on host plasma membrane, cytosol, and endosomal membrane.
Which PRRs are soluble?
CRP, C3, SAP
Why are the locations of the PRRs important?
Extracellular pathogens bind to the PRR on the CM (toll-like receptor); Viral PAMPs are expressed in the cytosol.
What is a Damage-Associated Molecular Patterns (DAMPs)?
Molecules released when a host cell/tissues become damaged or undergo necrosis. Innate cells have receptors for these; Stimulates removal of damaged tissues and wound healing.
Describe the process once a TLR is bound by a PAMP.
The intracellular portion of the TLR recruits NF-kB or Interferons (Anti-viral); Increased expression of cytokines which in turn causes inflammation and adaptive immunity.
In a TLR2 deficiency, what a patients in danger of?
They have an increased susceptibility to Gram positive infections; Strep pneumoniae meningitis.
How can defects in TLR signaling pathway present?
- Inappropriate activation of inflammation (autoimmune arthritis, asthma, septic shock)
- Persistent inhibition of activation; Recurrent infections, failure to thrive.
Which cells produce IFN-a and Beta?
IFN-a are produced by epithelial and B cells, macrophages, dendritic cells.
IFN-B are produced by fibroblasts
How common is it to have a interferon receptor?
Almost all cells have receptors for Type 1 interferons; Binding of IFN-a or beta activates signal transduction pathways, resulting in the production of enzymes that promote an anti-viral state.
Do interferons prevent viral entry into a cell?
NO; They just prevent viral replication.
What is the role of the NK cell?
They control intracellular pathogens during the early stages of the infection; Activated by Type-1 IFN receptors, PAMP receptors) NK cells DO NOT PHAGOCYTOSE.
How do NK cells kill virally infected cells?
They use granules directed at the cell.
Describe how macrophages and NK cells can work together.
A macrophage with phagocytosed microbes secretes IL-12 to NK cells. NK cells then secrete IFN-y to macrophage which makes it kill the phagocytosed microbe.
