innate immunity and granulocyte physiology part 1 Flashcards
what is innate immunity?
the first defence against foreign invaders present from birth not learned or adapted from exposure
what are the components of the innate immune system?
physical barriers (tight junctions in skin, epithelia surface)
phagocytes (neutrophils and macrophages)
granulocytes (neutrophils, eosinophils and basophils)
natural killer cells
serum proteins eg complement lectins
antimicrobial proteins (on the surface of cells or in phagocyte granules)
enzymes ( in epithelial cells and phagocytic cells)
what is the importance of the innate immune system?
the generation time of most bacteria is 20-30 minutes- the development of specific adaptive responses takes days to weeks. innate protects the host from the time of microbe exposure to initial adaptive responses
what is adaptive immunity?
second defence- specific and efficient lymphocytes
what does the adaptive immune system consist of?
cellular immunity- T cells and their secreted cytokines
humoral immunity- B cells and their secreted antibodies
what is microbial detection: pattern recognition?
pattern recognition receptors (PRR’S)- interact with components specific to microbes (pathogen associated molecular patterns)
PAMP’S are only produced by microbes, invariant structures and shared by entire classes of pathogens, ususally fundamental to survival/pathogenicity example. lipopolysaccharide (LPS)
what are the types of PRR’S?
- secreted and circulating PRR’S- (antimicrobial peptides, collectins, lectins and pentraxins)
- cell associated PRR’S- (example toll like receptors, PRR’S linked to phagocytosis)
what is the innate immune response largely mediated by ?
PRR’S that interact with components specific to microbes
fundamental to survival - microbes cant mutate its PAMP’S to avoid host defence mechanisms and still survive.
what is lipopolysaccharides?
bacterial endotoxin in outer membrane of all gram negative bacteria
contributes to structural integrity and protects bacterium
what are the functions of antimicrobial peptides (AMPS)?
important in the protection of skin and mucosal membranes and in killing phagocytozed organisms
AMPs secreted onto epithelial surfaces at site of injury create microbicial shield (bacteria, fungi, parasites, enveloped viruses)
AMPs form pores through outer membranes of microbes
All contain clusters of hydrophobic, +vely charged aa that bind to –vely charged phospholipids in outer bilayer of bacterial membranes
Animal cell membranes contain lipids that differ from microbes and AMPs are not attracted to them.
What are defensins (AMPS)?
alpha azurophilic granules of neutrophils- released into phagocytic vacuole with captured organisms. may kill microbes directly or form nanonets that trap microbes.
beta - expressed on all epithelial surfaces (airways, UT, GIT, mouth, cornea, skin) constitutive or inducible (injury elicits cytokines that induce)
what does bacterial permeability - increasing protein do?
expressed in neutrophil azurophilic granules and in oral, lung and GIT mucosal surfaces; damages membrane surfaces of gram negative bacteria and can opsonize bacteria for phagocytosis by neutrophils.
what are examples of ‘injury’?
infections/trauma
what are defensins?
toxicity due to membrane permeabilisation of target cell
what is the definition of opsonisation?
A major function of AMPS is to govern the composition of commensal organisms that colonise our body surfaces (lack attributes of major pathogens and relatively resistant to AMPS)
