innate immunity Flashcards
what is innate immunity?
nonspecific defense mechanisms that come into play immediately or within hours of an antigen’s appearance in the body
what are the 5 disease causing agents?
- bacteria
- virus
- protozoa
- fungi
- helminth
what 4 antimicrobial peptides present in the mouth act as a barrier to pathogens?
- immunoglobulins (IgA)
- lactoferrin
- lysozyme
- cystatins
what type of immune proteins is IgA?
antibody
why is IgA different from other antibodies?
it doesn’t require T/B cell interaction
how does IgA work?
bins to antigen preventing motility and attachment to muscosal surface
what type of receptors are bacteria recognised by?
toll-like receptors and NOD-like receptors
which type of receptor are viruses recognised by?
toll-like
what type of receptors are fungal pathogens recognised by?
dentin and gluten receptors
what are toll-like receptors (TLR)
pattern recognition receptors involved in the innate response
what are cytokines?
signalling molecules that coordinate the immune response
cytokines are said to be involved in autocrine signalling, what does this mean?
alter the behaviour of the cell by which they are secreted from
cytokines are said to be involved in paracrine signalling, what does this mean?
alter behaviour of neighbouring cell
cytokines are said to be involved in endocrine signalling, what does this mean?
enter circulation and alter behaviour of distant cells
what are chemokines?
small signalling proteins that recruit cells to site of inflammation by chemotaxis
what is chemotaxis?
movement of organisms in response to chemical stimuli
which two molecules dictate and shape immune response?
chemokines and cytokines
what are neutrophils?
most abundant granulocyte and WBC, they engulf and destroy invading pathogens
neutrophils are which type of immune cell?
phagocyte
neutrophils are attracted to the site of inflammation by which chemical?
IL-8
what is the difference between a macrophage and a monocyte?
macrophages are monocytes that reside in tissues instead of blood
what is the function of macrophages?
antigen presenting, phagocytose, release antimicrobials and enzymes, clearance of damaged tissues and cells
are neutrophils antigen presenting?
No
are macrophages antigen presenting?
yes
what are granules?
vesicles containing performed mediators (proteinases, antimicrobials, chemical mediators)
what is the function of mast cells and what immunological process do they lay a key role in?
allergy- release histamine
by which mechanism do mast cells release histamine?
undergoing degranulation
what is the function of phagocytes?
breakdown pathogens, remove pathogens from tissue and antigen present
describe the process of phagocytosis?
- chemotaxis and adherence of microbe to phagocyte
- phagocyte engulfs and ingests microbe
- phagosome forms (phagocytic vesicle)
- phagosome fuses with lysosome to form phagolysome
- enzymes in lysosome digest the microbe
- indigestible material is held within a residual body which is discharged as waste
- antigen presentation
what promotes the transport of immune cells through the endothelial cell wall into tissue ?
adhesion factors
what are the 4 enzyme cascade systems?
- complement
- kinin
- coagulation factors
- fibrinolytic system
how many plasma and cell proteins are in the complement system?
> 30
what is the main function of the complement system?
enhance our immunity
there are 3 complement system pathways, what re they?
- classical
- alternative
- lectin
how is the classic complement pathway triggered?
antibody attaching to microbe
how is the alternative complement pathway triggered?
C3b protein binds directly to microbe
how is the lectin complement pathway triggered?
mannose sugar binding lectin
all complement system pathways impinge on which enzyme cleaving what molecule?
C3 converts cleaving C3
where are the complement proteins mainly synthesised?
liver
what is the final product of the complement pathway?
membrane attack complex (MAC)
what is the name of the process by which white blood cells can squeeze through tight junctions between endothelial cells into tissues?
diapedesis
by what term are complement proteins C3a and C5a better known?
anaphylatoxins
what 3 specific signals so CD4 cells require to become activated and differentiate?
signal 1 - peptide antigen (presented by MHC II) interacts with cognate T cell receptor
signal 2 - CD28 interacts with CD80/86 expressed on mature dendritic cells
signal 3 - cytokines
