Review of innate system Flashcards by BLACK H

Why is the adaptive immune system not apt for new pathogens?

→too slow

How well did you know this?

Not at all

Perfectly

Compare innate and adaptive immune system

→Adaptive immunity – involves very specific recognition of infectious agent
→Innate immunity – no specific antigen recognition

→Innate immunity involves recognition of broadly conserved features of different classes of pathogens

How well did you know this?

Not at all

Perfectly

How is pattern recognition done in innate response?

→PAMPs

How well did you know this?

Not at all

Perfectly

What are PAMPs?

→Molecules present only on pathogens and not on host cells

→Essential for survival of pathogens

→Invariant structures shared by entire class of pathogens

How well did you know this?

Not at all

Perfectly

What type of bacteria have PAMPs?

→gram negative or positive

How well did you know this?

Not at all

Perfectly

Example of PAMPs in gram negative bacteria

→lipopolysaccharides (LPSs) outer membrane

How well did you know this?

Not at all

Perfectly

Examples of gram positive bacteria cell wall components

→teichoic acid
→lipoteichoic acid
→peptidoglycan found in outer membrane

How well did you know this?

Not at all

Perfectly

What are other PAMPs?

→Bacterial flagellin
→Abnormal protein glycosylation
→Abnormal nucleic acids - viruses

How well did you know this?

Not at all

Perfectly

What are PRRs?

→Host factors that specifically recognise a particular type of PAMP

How well did you know this?

Not at all

Perfectly

How are PRRs encoded?

→germ line encoded

→no rearrangement unlike antibodies

How well did you know this?

Not at all

Perfectly

What are the 3 types of PRRs?

→Extracellular
→intracellular
→secreted

How well did you know this?

Not at all

Perfectly

What are secreted PRRs?

→they act to tag circulating pathogens for elimination

→eg complements

How well did you know this?

Not at all

Perfectly

What are the components of innate immunity?

→The inflammatory response
→Phagocytes
Monocytes/granulocytes/neutrophils
→Complement
→Cytokines, chemokines and anti-microbial peptides (AMPs)
→Natural Killer cells

How well did you know this?

Not at all

Perfectly

What is an inflammatory response?

→localize and eliminate injurious agents and to remove damaged tissue components

How well did you know this?

Not at all

Perfectly

What are the features of inflammatory response?

→Enhanced permeability and extravasation
→Neutrophil recruitment
→Enhanced cell adhesion
→Enhance clotting

How well did you know this?

Not at all

Perfectly

What is the inflammatory response trigger?

→the release of pro-inflammatory cytokines and chemokines

How well did you know this?

Not at all

Perfectly

What is the difference between cytokines and chemokines?

→cytokines enhance inflammatory

→chemokines act to create chemical concentration gradient for neutrophils to migrate to

How well did you know this?

Not at all

Perfectly

What are TLRs not involved in?

→phagocytosis

How well did you know this?

Not at all

Perfectly

What is a distinct feature of phagocytic recognition?

→they use different pattern recognition receptors

How well did you know this?

Not at all

Perfectly

What are neutrophils involved in?

→Neutrophils involved in tissue damage not involved in priming adaptive response

How well did you know this?

Not at all

Perfectly

What are the three distinct roles of macrophages and dendritic cells?

→Phagocytosis; material is destroyed in lysosomes
→activated macrophages produce cytokines and chemokines

→Peptides from broken down pathogens can be presented through MHC and promote the development or recall of an adaptive T cell response

How well did you know this?

Not at all

Perfectly

How do Phagocytes know what to eat?

→By detecting phosphatidylserine on exterior membrane surface (cells undergoing apoptosis)

→By detecting “atypical sugars” (e.g. mannose, fucose, b-glucan) on cell surfaces

→By Scavenger receptors

→By “passive sampling”

→By detecting complement
proteins bound to the
pathogen surface

What are examples of atypical sugars?

→mannose,
→fucose,
→b-glucan

Which virus doesn’t present phosphatidylserine?

→Ebola

What is the complement system?

→Complement proteins act as secreted Pattern recognition receptors (PRRs) →can be activated by a range of PAMPs, and can also be activated by “altered self”

Which organ makes the complement system?

→liver

What are the PAMP targets of the complement system?

``` →antigens →LPS →abnormal phospholipids →atypical glycosylation →lack of host control factors ```

What are the three pathways of complement system?

→The Classical Pathway →The Mannose-Binding Lectin Pathway →The Alternative Pathway

What is the classical pathway of complements?

→activated when a complement protein called C1q binds either directly to a pathogen, or onto an antigen-antibody complex

What do all the pathways have in common?

→produce C3 convertase

What is the MBL/ficolins pathway?

→detect carbohydrates containing mannose on the surface of pathogens, →activating a protease called MASP →MASP is responsible for cleaving complement components →activates cascade

What is the alternative pathway of the complement system?

→activated by bacterial endotoxin | →lipopolysaccharide present on the outer membrane of gram negative bacteria

How do Phagocytes know when they are infected and when to produce cytokines and chemokines?

→PAMPs are recognised by a distinct group of Pattern Recognition Receptors

What are the PRRs on phagocytes?

→TLRS →NOD-like →RIG like

What is the TLR ligands?

→LPS →Unmethylated CpG- viral infection →flagelin →dsRNA or ssRNA

What is the outcome of TLR activation?

→inflammation: cytokine release (TNF, IL-1, IL-12) →enhanced killing: reactive oxygen species, NO)

What are the ligands for NOD-like receptors?

→Peptidoglycan from Gram positive and negative bacteria →Some viral DNA and RNA (indirect?)

What is the outcome of NOD-like receptors?

→inflammation: cytokine release (IL-1, IL-8)

What is the outcome of RIG-like receptors?

→type I interferon production

What is the ligand for RIG-like receptors?

→Viral dsRNA and 5’-triphospho RNA(inproperly capped)

What are cytokines?

→Act to modify the behaviour of cells in the immune response →Most of these are called interleukins (eg. IL-1)

What do type 3 interferons protect?

→epithelial surfaces

What are interferons induced by?

→viral infection

How are interferons released?

→Secreted hormone factors (type I and type III)

What are anti-microbial peptides?

→Secreted short peptides (18-45 amino acids) →Offer broad protection →Some are induced by bacterial infection

How do anti-microbial peptides work?

→by disrupting cell wall leading to lysis

What are NK cells?

→Lymphocyte-like but larger with granular cytoplasm

What pathogens do NK cells kill?

→certain tumour | →virally infected cells

How do NK cells cause destruction?

→cytotoxic molecules called granzymes & perforins

How are NK cells activated?

→loss of self MHC molecules on target cell surfaces →upregulation of ligands

What are the two types of complement core defects?

→core defects (e.g. C3) linked to development of autoimmune diseases such as lupus →non-core defects linked to suseptibility to specific types of pathogens such as Neisseria

What are two macrophage deficiencies?

→Chronic granulomatous disease (CGD); No oxidative burst for bacterial killing →IRF8 mutations linked to susceptibility to TB

What is Aicardi-Goutieres syndrome?

→associated with constitutive production of inflammatory cytokines

What are the receptors used in innate and adaptive immunity?

``` →innate= pattern recognition →adaptive= Igs and TCR ```