Review of the Innate System Flashcards
Why do we need the inante immunity?
Adaptive immune response is too slow to protect us from some new pathogens
How long do antibodies and cytotoxic T cells take to begin to be seen in a new infection?
- Antibodies start around 5 days but take longer to accumulate
- Cytotoxic T cells start to rise on day 3/4 and peak soon
- So a fast replicating organism could form huge numbers in the first few days if it weren’t for innate immunity
What is the major class of antiviral cytokines?
Interferon
What does the innate immunity recognise?
PAMPs
Innate immunity can not recognise specific antigens such as proteins, so it instead recognises broadly conserved pathogenic features such as structural features of a cell wall
What is a PAMP?
Pathogen Associateed Molecular Pattern
is NOT a specific antigen like what the adaptive immune response identifies, it is broad pathogenic features
Name some features of PAMPs
- Molecules present only on pathogens and not on host cells
- Essential for survival of pathogens
- Invariant structures shared by entire class of pathogens
Name some PAMPs for gram positive bacteria
- Teichoic acid
- Lipoteichoic acids
- peptidoglycan found in outer membrane
Name a PAMP for gram negative bacteria
Lipopolysaccharides (LPSs) found in outer membrane
What PAMPs can we recognise for viruses as they do not have a cell wall?
They do not have a cell wall but we can recognise abnormal nucleic acids (or abnormal protein glycosylation also?)
What is meant by how PRRs are germ-line encoded?
They do not change unlike in T cells or B cells that rearrange their T or B cell receptors
What do PRRs recognise?
PAMPs
Name the 3 functional classes of PRRs
- Extracellular - recognise PAMPs outside cells
- Intracellular/cytoplasmic - recognise PAMPs inside a cell
- Secreted - tag circulating pathogens (like complement)
What is complement?
- A type of PRR that is secreted
- The complement system helps or “complements” the ability of antibodies and phagocytic cells to clear pathogens from an organism.
Broadly describe the purpose and effects of the inflammatory response
- A generic defence mechanism whose purpose is to localize and eliminate injurious agents and to remove damaged tissue components
- Enhanced permeability and extravasation
- Neutrophil recruitment
- Enhanced cell adhesion
- Enhance clotting
- Triggered by the release of pro-inflammatory cytokines and chemokines at the site of infection
Which WBCs are mostly recruited in inflammation?
Neutrophils
What are some requirements of phagocytes?
- need to be able to recognise what to eat
- need to know when they are infected
They do this by 2 SEPERATE mechanisms (they use different PRRs)
Name 3 professional phagocytes
Dendritic cells, macrophages and neutrophils
What are the 3 distinct roles of macrophages and dendritic cells in immunity?
- phagocytosis
- macrophages produce cytokines and chemokines to + innate and adaptive response and local inflammation
- MHC antigeen presentation (promote or recall of an adaptive T cell response)
What marker do phagocytes detect on an apoptotic cell?
Phosphatidylserine on the exterior membrane
This is a way of detecting virus-infected cells as an infected cell will usually apoptose
Macrophages detect atypical sugars such as {{?}} on cell surfaces
mannose, fucose and beta glucan
What are scavenger receptors?
Detect non-self markers, detect various PAMPs and DAMPs
What are scavenger receptors?
Detect non-self markers, detect various PAMPs and DAMPs
What is macrophage passive sampling?
Taking in small globules of ECF and sampling it for pathogens
{{?}} receptors are found on phagocytes to aid in the take up of complement-coated pathogens
Complement receptors are found on phagocytes to aid in the take up of complement-coated pathogens
