Review Of The Innate Immune System Flashcards
What does the innate immune system recognise?
Pathogen-associated molecular patterns (PAMPs)
What are the PAMPs on gram -ve bacteria?
Lipopolysaccharides found in the outer membrane
What are the PAMPs on gram +ve bacteria?
Teichoic acid
Lipoteichoic acid
Peptidoglycan
What are some general examples of PAMPs?
Bacterial flagellum
Abnormal protein glycosylation
Abnormal nucleic acids (in viruses)
What are pattern recognition receptors (PRRs)?
Host factors that specifically recognise a particular type of PAMP
What are the functional classes of PRRs?
Extracellular
Intracellular
Secretory
How do extracellular PRRs work?
Recognise PAMPs outside of a cell and trigger a co-ordinated response to the pathogen
How do intracellular PRRs work?
Recognise PAMPs inside a cell and at to coordinate a response to the pathogen
How do secretory PRRs work?
Tag circulatory pathogen for elimination
What are the components of innate immunity?
Inflammatory response Phagocytes Complement Cytokines, chemokines and anti-microbial peptides Natural killer cells
What is the inflammatory response pathway?
Enhanced permeability and extravasation
Neutrophil recruitment
Enhanced cell adhesion
Enhanced clotting
What is the inflammatory response triggered by?
release of pro-inflammatory cytokines and chemokines at the site of infection
How do phagocytes recognise pathogenic cells?
Detecting phosphatidylserine on exterior membrane surface
Detecting atypical sugars
Scavenger receptors
Passive sampling
Detecting complement proteins bound to the pathogen surface
What is the role of macrophages in infection?
Activated macrophages produce cytokines and chemokines
-> stimulate both innate and adaptive immune responses
What are the pathways in the complement system?
Classical
Lectin
Alternative
What happens in the classical complement pathway?
Recognises antigens and lipopolysaccharide polyanions
What happens in the leptin pathway complement system?
Recognises atypical glycosylation
What happens in the alternative complement pathway system?
Lack of host control factors
What are the types of PRRs?
Toll-like receptor
NOD-like receptors
RIG-like receptors
What do the toll-like receptors target?
DsRNA, ssRNA
What do NOD-like receptors affect?
Some viral DNA and RNA
What do RIG-like receptors target?
Viral dsRNA and 5’-triphosphoRNA
What are cytokines and chemokines?
Glycoprotein hormones that affect the immune response
What do cytokines act to do?
Modify the behaviour of cells in the immune respose
What do chemokines act as?
Chemotactic factors that create concentration gradients which attract specific cell types to a site of production/infection
What are interferons?
Main antiviral cytokines
What is the interferon system?
Virus replicates inside the cell
Cell lyses and releases interferon and viral progeny
Interferon binds to neighbouring cells triggering the transcription of lots of viral genes
Virus then tries to infect new cells in the environment, causing translational arrest
What are antimicrobial peptides?
Secreted short peptides that usually work by disrupting cell wall leading to lysis
What are natural killer cells activated by?
Loss of MHC class 1 molecules on target cell surfaces and up-regulation of activating ligands
What are diseases associated with complement defects?
Core defects linked to a development of autoimmune diseases such as lupus
Non-core defects linked to susceptibility of specific types of pathogens such as neisseria
What are diseases associated with macrophage deficiency defects?
Chronic granulomatous disease
IRF8 mutations linked to susceptibility to TB
What causes aicardi-goutieres syndrome?
Constitutive production of inflammatory cytokines
