Innate Immunity Flashcards
describe innate immunity
this is the first line of defence, and has no memory or lasting protection
it is present from birth
effective as there is regular contact with potential pathogens
recruits immune cells to sites of infection
why is innate immunity described as non specific
the responses are broad spectrum
what do commensals do
these elicity low level immune responses
describe the series of events for immediate innate immunity
infection
recognition performed, non specific and broadly specific effectors
removal of infectious agent
describe the series of events in early induced innate responses
infection
recruitment of effector cells
recognition of PAMPs
activation of effector cells and inflammation
removal of infectious agent
describe the series of event in the adaptive immune response
infection
transport of antigen to lymphoid organs
recognition by naive B and T cells
clonal expansion and differentiation to effector cells
removal of an infectious agent
what are some compounds produced from epithelial barriers in the mouth
antimicrobial peptides
secetory IgA
lactoferrin
lysozyme
cystatins
what are the major families of antimicrobial peptides
B-defensins
human neutrophil peptides
cathelicidins
describe the response of immune modulation
monocytes, neutrophils and dendritic cells activate, attract and differentiate leukocytes
summarise secretory IgA
produced at mucosal surfaces
found in saliva
binds to flagella, can prevent motility
binds to and neutralises bacterial toxins
prevents attachment of bacteria to mucosal surfaces
what is lactoferrin
glycoprotein that transports iron ioons but has antimicrobial activity
present in saliva
produced by neutrophils
what is lysozyme
present in saliva
produced by macrophages and neutrophils
target cell walls of bacteria
what are cystatins
anti protease activity and support of remineralisation of the teeth
what protects epithelium
salivary components with antimicrobial activity
what are some examples of effector responses
phagocytosis
antigen presentation
degranulation
soluble mediators
what are antigens
receptors on immune cells for components of microorganisms
what are microbial antigens
toxins and virulence factors
what drives immune response
immune receptor activation
what are the main receptor types
toll like receptors
which toll like receptors aid in fungal recognition
dectin and glucan receptors
which receptors aid in bacterial recognition
NOD like receptors
which receptors aid in allergen recognition
protease activated receptors
what is PAMPS
pathogen
associated
molecular
patterns
what is PRRs
pattern recognition receptors
what are the soluble mediators produced by immune cells
cytokines and chemokines
complement proteins
antimicrobial peptides
enzymes
prostaglandins
leukotrienes
immunoglobins
growth factors
matrix mellatoproteinases
what are cytokines
small proteins
these are signalling molecules that coordinate immune responses
can be autocrine, paracrine or endocrine
what are the cytokine families
interleukin
TNF
interferons
unassigned
how do cytokines signal
through cytokine receptors.
the binding of cytokines induces conformational changes to lead to cell programming
what are chemokines
small signalling proteins predominantly involved in cell recruitment and direction
what is chemotaxis
the movement of a cell in the direction corresponding to a gradient of increasing/decreasing concentration of a substance
how do chemokines signal
through chemokine receptors on immune cells
what proteins is tissue homeostasis largely dependent on
cytokines and chemokines
what do pattern recognition receptors do
these recognise unique features of microbes and initiate inflammatory responses via activation of intracellular signalling pathways
this leads to switching on of genes
what is included in the immune cell network
epithelial cells
dendritic cells
macrophages
neutrophils
mast cells
NK cells
what is the main function of the immune cell network
microbial recognition and effector responses
what are the pattern recognition receptor types
toll like receptors
dectin receptors
what happens once there is receptor activation
intracellular signalling cascades, transcription, protein translation and effector responses
which form of immunity gives immunological memory
adaptive immunity
how long for an innate response
arise from a few hours up to a few days
why is the innate immune system extremely effective
the immune system comes in contact with many pathogens on a daily basis
what are the professional immune cells
defence cells
what are the non professional immune cells
epithelial cells that are the first thing the potential pathogen comes in contact with
also endothelial cells and fibroblasts
what is the innate immune system developed to do
recognise what is a commensal organism and what is a potential pathogenic organism
what is a commensal organism
a microorganism that does not cause disease
what is tissue homeostasis
the balancing out of inflammation levels
where are dendritic cells and macrophages found
beneath the epithelium
when does the apative immune system become active
persistent pathogen
what is the cellular barrier to infection
microbial recognition
what is the initiating factor for inflammation
microorganisms
what is the physical and anatomical barrier to infection
epithelium
describe the killing action of LL-37
cathelicidin
spiral shape inserted into the cell membrane of the potential invading pathogen
once inserted, it will disrupt the membrane and lead to lysis of the cell
what is the method of destruction for antimicrobial peptides
inserting into the membrane to disrupt it and lead to cell lysis
internalise themselves to infere with normal function of the cell
modulate the immune system to activate cells and increase attraction of circulating immune cells to the site of infection
why can secretory IgA prevent the binding of bacteria to mucosal surfaces
can prevent the binding because of its structure as it has four binding sites. the four sites allow the secretory IgA to bind them and cult an invading pathogen to prevent it from attaching to the target epithelium
what are effector responses examples of
what can occur in the innate immune system
what leads to effector responses
microbial recognition
what are the two components of innate immunity
epithelium and innate immune cells
which substances orchestrate immune responses
cytokines and chemokines
what is the name given to receptors that recognise uniqu features of microbes
pattern recognition receptors
where are the immune cells present in the oral mucosa
- tissue resident
- from circulation
what are the main cells in the oral mucosa that function in defense and immunity
neutrophils
what is the most abundant defense cell type
neutrophils
how do neutrophils know where the infection is
they are attracted along a CXCL8 gradient to the site of inflammation
what is diapedesis
migration of immune cells out of circulation into blood vessel cell walls
what are the receptors on the immune cells and endothelial cells
selectins
integrins
immunoglobin superfamily
what are some mediators
- cytokines
- chemokines
- complement proteins
- antimicrobial peptides
- enzymes
- prostalglandins
- leukotrienes
- immunoglobins
- growth factors
- matric metalloproteinases
how are some mediators released
through degranulation
what are chemokines as a form of cytokines
chemotactic cytokines
how does innate immune system respond
through effector responses
what are granules
vesicles containing mediators
what are found in granules
mediators like proteinases, antimicrobials and chemical mediators
what moves neutrophils
chemokines, mainly interleukine 8. neutrophils move from an area of low concentration to high concentrations of the interleukin.
how do neutrophils get to the site of infection from circulation
via blood vessel walls.
lymphocyte function associated antigen 1 is found on neutrophils to interact with endothelial cell receptors to get out of circulation
what are the chemical mediators
leukotrienes
nitric oxide
histamine
what is tissue homeostasis
this is the immune system working at an optimal level where it isnt overactive or underactive.
cytokine and chemokine balance is essential for this
what are the main cell types that undergo degranulation
eosinophil
basophil
neutrophil
nk cell
mast cell
describe what happens in degranulation
release of vesicles from the cell membrane, which contain soluble mediators.
why can basophils and eosinophils take up parasites
they are larger than most
why are basophils, eosinophils and mast cells associated with allergic reactions
they all release histamine
what are the main roles of degranulation
vasodilation
increased vascular permeability of blood vessels
smooth muscle contraction
bronchoconstriction
neurotransmission (sensation of itching in allergies)
what is NETosis
the mechanism of NET production, whereby the neutrophil produces proteins and genetic material to make an extracellular matrix that acts as a cobweb to encapsulate microbes
what process is NETosis an example of
degranulation
what are NETs
neutrophil extracellular traps
what does activation of neutrophils lead to
release of proteins and chromatin to form a fibril matrix
describe how natural killer cells lyse other cells
they release perforin to form a pore in the invading cell to allow granzymes to enter, break down its proteins and cause lysis of the cell.
what is ADCC
antibody dependent cellular cytoxicity
what is ADCC describing
lysis of the infected cell
what is phagocytosis
a process utilised by phagocytes, cells like neutrophils, macrophages and dendritic cells
what are the main roles of phagocytosis
degradation and removal of pathogenic threat
antigen presentation
break down and dispose of apoptopic cells
what are the stages to phagocytosis
recognition
engulfment
phagosome
phagolysosome
cell digestion
residual bodies
exocytosis
describe what happens in phagocytosis
Recognition of the microbe leads to engulfment which arises due to change in cell morphology. The cytoskeleton changes structure to allow for the engulfment. Once it has been engulfed, it will be stored in phagosome (phagocytic vesicle). Lysosome involved in step four to combine with phagosome to form phagolysosome to allow for the beginning of degradation of the invading microbe. Cell digestion is further degradation of the microbe, where it could be processed for antigen presentation. 4/5 can lead to antigen presentation or release of the components back into circulation after degradation. Residual bodies are indigestible that are released by the cell.
what are the two receptors involved in antigen presentation
MHC1 and MHC2
what do MHC1 receptors do
presentation of endogenous proteins like viral and tumour cells found on all nucleated cells in the host body
what do MHC2 receptors do
involved in presentation of exogenous proteins
usually arises after phagocytosis
bacteria, fungi and parasites for example
what are the three cells in the human body that can use MHC2 receptors to drive antigen presenting
dendritic cells, macrophages and B cells
what does CD8+ do
drive cytoxicity to lead to lysis of the cells which is important endogenously
what do CD4+ do
T helper cells to provide immunological memory for any exogenous proteins from bacteria, fungi and parasites
what antigen presentation essential for
the link between innate and adaptive immunity - T cell and B cell responses are driven by this interaction at MHC surface
describe t cell response
cell mediated
describe b cell response
humoral
what is the largest component of human blood
plasma
what is contained in plasma
four connected, enzymatic cascade systems
what are the enzymatic cascade systems within plasma
complement
kinins
coagulation factors
fibrinolytic system
what are complement proteins
soluble mediators present in the circulation that are produced in the liver and released into circulation
what is opsonisation
coating of an invading pathogen with C3B, giving rise to specific receptors for the protein on defence cells to drive phagocytosis
what is the membrane attach complex
collection of complement proteins forming on the surface of a microbe
what are the three main roles of complement proteins
opsonisation
inflammatory responses
membrane attach complex
what are the three pathways of complement
classical pathway
alternative pathway
mannose binding lectin pathway
what is the initiating factor for the classical complement pathway
antibody attached to a microbe
what is the initiating factor for the alternative complement pathway
microbial cell wall
what is the initiating factor for the mannose binding lectin pathway
microbial carbohydrates
what is the name for complement proteins
anaphylatoxins
what is the name for the process whereby neutrophils and other immune cells migrate to the site of infection
diapedesis
what are the main effector responses arising from microbial recognition
degranulation
phagocytosis
antigen presentation
