Innate Immunity 2 Flashcards
what are cytokines?
small proteins that act as signalling molecules to co-ordinate immune responses
what are chemokines?
small proteins that are involved in directing cells to the site of infection
give an example of a cell that is both chemokine and cytokine
IL-8 / CXCL8
what is the most abundant cell type at the oral mucosa?
neutrophils
what do neutrophils do during inflammation?
they increase in number and they are attracted along a CXCL8 gradient to the site of inflammation
what do cell adhesion molecules do?
control interactions between immune cells and endothelial cells
what are the three main families of cell adhesion molecules?
selectins, integrins and immunoglobulin superfamily
what do cell adhesion molecules promote and what are they important for?
promote cell-cell interactions and are important for immune trafficking
what are endothelial cells?
cells that line the interior surface of blood vessels and lymphatic vessels
where are selectins and immunoglobins found?
on endothelial cells
where are integrins found?
on migrating immune cells
what is the primary funciton of neutrophils?
to engulf and destroy invading pathogens
what do granules contain?
degradative enzymes and antimicrobial substances
what is degranulation?
when the granules are released upon activation of receptors
what happens when neutrophils are activated?
it induces them to release proteins and some genetic material (chromatin) to form extra-cellular fibril matrix which TRAPS PATHOGENS
what do monocytes do?
circulate in the blood as precursors to macrophages
what is the primary function of macrophages?
phagocytosis as well as presentation of antigen to adaptive immune cells
what is the function of mast cells?
degranulation
what is the function of dendritic cells?
present antigen to T cells
what cells contain granules?
mast cells, natural killer cells, monocytes, macrophages and neutrophils
what are granules?
vesicles containing preformed mediators
what preformed mediators are contained within granules?
proteinases, antimicrobials, chemical mediators
what are the preformed mediators in the granules in response to?
MAMPs (e.g. microbial antigens), complement proteins, cytokines and other inflammatory mediators
what is phagocytosis?
degradation and removal of pathogenic threat, antigen presentation, safe break down and disposal of apoptotic cells
what are the 2 types of antigen presenting cells?
non-professional and professional
give an example of a non-professional APC
epithelial cells/fibroblasts/endothelial cells
give an example of professional APCs
macrophages and dendritic cells
what is the first step of phagocytosis?
CHEMOTAXIS and adherence of microbe to phagocyte
what is the second step of phagocytosis?
INGESTION of microbe by phagocyte
what is the third step of phagocytosis?
FORMATION of a phagosome
what is the fourth step of phagocytosis?
FUSION of the phagosome with a lysosome to form a phagolysosome
what is the fifth step of phagocytosis?
DIGESTION of ingested microbe by enzymes
what is the sixth step of phagocytosis?
formation of RESIDUAL BODY containing indigestible material
what is the seventh step of phagocytosis?
DISCHARGE of waste materials
what happens to the degraded waste material in non-APCs
released and sometimes picked up by APCs
what happens to the degraded waste material in APCs?
it is processed for antigen presentation
what is the first step of antigen presentation?
a pathogen or extracellular antigen s phagocytised by an APC and placed into a vesicle. Ingested pathogens are digested by lysosomes to extract their antigens
what is the second step of antigen presentation?
the antigens bind with MHC proteins that enter the vesicle
what is an MHC protein?
major histocompatibility complex
what is the third step of antigen presentation?
the MHC proteins, now carrying antigens, are released from the vesicle and travel to the outer surface of the cell membrane
what is the fourth step of antigen presentation?
the APC cell is now presenting antigens which will activate T cells that bind with the MHC proteins
what are the 4 enzymatic cascade systems of plasma factors?
complement, kinins, coagulation factors, fibrinolytic system
what do the 4 enzymatic cascades produce?
inflammatory mediators
what is complement?
a collection of soluble proteins present in circulation
what does complement do?
drives inflammation or opsonisation
what is opsonisaion?
the coating of pathogens by antibodies or complement proteins
what are the 3 pathways of complement?
classical, alternative and lectin
what is the initiating factor of the classical pathway of complement?
antibody attached to microbe
what is the initiating factor of the alternative pathway of complement?
microbial cell wall
what is the initiating factor of the lectin pathway of complement?
carbohydrates on pathogen surface
what do anaphylatoxins lead to?
smooth muscle contraction and capillary leakage - allowing increased infiltration of immune cells to site of infection
what do all the complement pathways lead to?
the formation of C3 and C5 convertase enzymes
what are the steps of complement?
binding of complement proteins to microbial cell surface or antibody - formation of C3 convertase - cleavage of C3 - formation of C5 convertase
what do C3 and C5 convertase enzymes do?
degrade C3 or C5 proteins
what are anaphylatoxins?
glycoproteins such as complement components C3, C4 and C5 (and their fragments) that drive immune response
what do anaphylatoxins do?
promote immune cell recruitment, increase adhesion of cells to vessel walls, induces granulation, promotes cytokine production, induces antigen presentation and regulates adaptive immune responses
how to neutrophils, monocytes and other immune cells migrate to site of infection?
via cell surface receptors on endothelial cells (selectins, integrins and immunoglobulin superfamily)
what are the three main process involved in innate immunity?
degranulation, phagocytosis and antigen presentation
why is complement important?
for innate and adaptive immune responses
