Innate Immunity 2 Flashcards
What do cytokines do and what do chemokines do?
Chemokines direct cells to site of infection and cytokines tell cells what to do when they arrive at the site of infection
What are the most abundant cells at oral epithelium that increase during inflammation?
neutrophils
Where are most of immune cells in oral cavity?
oral tissues such as tonsils, buccal epithelium, palate
What attracts neutrophils to site of inflammation?
interleukin 8 (IL-8)
What controls interactions between immune cells and the endothelial cells they have to pass by?
cell adhesion molecules
What are the families of cell adhesion molecules
Selectins (e.g., P and E- selectins)
Integrins (e.g., LFA-I)
Immunoglobulin superfamily
What immune cells have select receptors/ligands that allow migration?
monocytes
dendritic cells
What are neutrophils?
phagocytic granulocytes
What do granules contain?
contain degradative enzymes and antimicrobial substances
What are the two main functions of neutrophils?
degranulation
NETs (neutrophil extracellular traps)
How are granules/vesicles released from neutrophil?
Released upon activation of receptors (e.g. TLRs)
When NET pathway is activated, what occurs?
induces neutrophils to release proteins and some genetic material (chromatin) to form extra-cellular fibril matrix to trap pathogens
What is chromatin?
clump of nucleic acids
How do monocytes migrate to tissues?
similar to neutrophils
via cell adhesion molecules
What are the subsets of macrophages?
Pro- and anti- inflammatory subsets (M1 – pro- and M2 – anti-)
What is an example of an anti-inflammatory cell subset?
regulatory T cell
What is phagocytosis?
digestion of microbial cells, and degradation – can present antigen to adaptive immune cells
What is the primary function of macrophages?
phagocytosis as well as presentation of antigen to adaptive immune cells
What are the two types of APC and what do they include?
Non-professional (Epithelial cells/fibroblasts/endothelial cells)
Professional (Macrophages, dendritic cells, B cells)
What do cells have that allow attachment to microbes?
Tentacle like structures – help attachment to microbes
What cells carry out phagocytosis?
neutrophils, macrophages/monocytes, dendritic cells, and B cells
How does phagocytosis occur?
Microbes are internalized in a phagosome and digestive enzymes from lysosome(vesicle) help to degrade microbe
What happens to the degraded waste material in both APCs and non APCs?
In non antigen presenting cells (e.g., neutrophils generally are not considered APCs) the degraded waster materials are released – sometimes these discarded materials (e.g., microbial antigens) are picked up by APCs
In antigen presenting cells (e.g., macrophages and DCs) the degraded waste material is processed for antigen presentation on MHC receptors.
What is a phagosome?
phagocytic vesicle
What does the fusion of a lysosome and phagosome create?
phagolysosome
What receptor does the T cell recognise the antigen by?
MHC (I or II)
How do APCs work?
dendritic cell internalizes and degrades antigen into linear peptides
linear peptides presented on cell Surface attached to MHC (major histocompatibility complex) Class I or II
What are the differences between MHC I and MHC II?
MHC II are for intracellular and extracellular bacteria/fungi (found only on APCs for interaction with T helper cells)
MHCI are for virally infected cells (found on all cells for interaction with cytotoxic cells)
What are granules and what do they contain?
Granules are vesicles containing preformed mediators;
Proteinases
Antimicrobials (AMPs, lactoferrin etc.)
Chemical mediators (e.g., histamine)
What do granules respond to?
MAMPs (e.g., microbial antigens)
Complement proteins
Cytokines and other inflammatory mediators
What are the 4 enzymatic cascade systems of plasma?
Complement
Kinins
Coagulation factors
Fibrinolytic system
What do plasma systems produce?
various inflammatory mediators
What is opsonisation?
coating/tagging of a microbe for removal by antibodies or complement proteins(capsulated organisms are protected)
Describe the complement system
A collection of soluble proteins present in circulation.
Drives inflammation or opsonisation
Three pathways; classical, alternative or lectin pathway
What are the 3 pathways of complement and how do they work?
(1) Classical pathway – antibody attached to microbe
(2) Alternative pathway – microbial cell wall
(3) Mannose binding lectin pathway (MBL) – carbohydrates on pathogen surface
What are anaphylatoxins?
Glycoproteins such as complement components C3, C4 and C5 (and their fragments) that drive immune responses
What do anaphylatoxins lead to?
Anaphylatoxins lead to smooth muscle contraction and capillary leakage – allowing increased infiltration of immune cells to site of infection
What do all pathways form?
C3 convertase and C5 convertase enzymes
What do C3 convertase and C5 convertase enzymes degrade?
C3 or C5 protein
What are the roles of anaphylatoxins?
Promote immune cell recruitment
Increase adhesion of cells to vessel walls
Induces granulation
Promotes cytokine production
Induces antigen presentation
Regulate adaptive immune responses
What can possibly lead to resolution of PD in mice?
loss of complement system
