Innate Immunity Flashcards
adaptive response
- soluble receptors: antibodies
- cell receptors- B/T cells
Innate response
- soluble: complement, pentraxins, collecting, fictions
- cell receptors: TLR, Nod-like etc
immunity requires
recognition and elimination- containment
most of the mechanisms against infectious agents
are provided by innate immune system
what recognise PAMPs
Pattern Recognition receptors
innate responses are
activated within hours of contact, but not signify increased by previous exposure
pathogens are capable of
-colonising the cytoplasm, intracellular vesicles, intersistital spaces, blood, lymph and epithelial surfaces
first critical barrier is
the skin- cuts, abrasions, burns expose body to bacterial, viral and fungal infections that can be fatal
main portals of entry for pathogens
-mucosal epithelia of gastrointestinal, respiratory and urogenital tracts
cells of the innate and adaptive immune system are derived from
pluripotent hematopoeitic stem cells
immune cell differentiation process
1) hematopoietic stem cells divide to produce a progenitor cell with the potential to give rise to all the hematopoietic lineages
2) generation of further progenitor cells committed to progressively narrower ranges of differentiated fates
both WBC and RBC are derived from
hematopoietic stem cells via committed progenitors which give rise to erythroid, myeloid and lymphoid lineages
THE ERYTHROID LINEAGE
gives rise to the erythrocytes and to megakaryocyes which shed fragments that form the platelets- that initiate blood clotting
THE MYELOID LINEAGE
gives rise to phagocytes and inflammatory cells of innate immunity
THE LYMPHOID LINEAGE
gives rise to the T and B cells of the adaptive immune system
activation of innate immune system
-invoked either directly by a pathogen, or by the adaptive immune response
indirect activation of the innate immune system
a lymphocytes o te adaptive immune system produces antibodies whose variable regions recognise a surface component of the bacterium. A non-variable region of the antibody is then recognised by a receptor of the phagocyte, which in turn is activated to engulf it.
- in this way bacteria that have masked the conserved component can be recognised and destroyed by the innate immune system
opsonin
a general term for soluble
components of the immune
system e.g. IgG1 that coat micro-organisms
and stimulate uptake by phagocytes
process of opsonisation
1) binding of soluble opsonins to particle
2) particle binding via phagocytic receptor
3) particle engulfment with actin polymerisation
4) interlization
5) fusion of phagosome with primary, secondary granules and lysosomes–> destruction
why are phagocytes important
1) when they sense PAMPs they release cytokines and chemokines that amplify response to infection (e.g. increasing permeability of blood vessels and recruiting additional cells - inflammatory response)
2) they activate the adaptive immune system e.g. dendritic
Ilya Mechnikov
discovered phenomenon of phagocytosis
1) observed mobile cells in larvae of starfish
2) introduced small thorns rom tangerine tree which had been prepared as a christmas tree for his children
3) next morning he found the thorns surrounded by the mobile cells
4) he knew that when inflammation occurred in animals, with a vascular blood system- leucocytes escaped from their blood vessels
5) occurred to him that leucocytes might take up and digest the bacteria that get into the body
three lineages of the Hematopoietic stem cell lineages
- myeloid
- lymphoid
- erythroid
myeloid cells are
innate
name 8 myeloid cells
- mast
- macrophage
- dendritic
- mast
- neutrophil
- eosinophil
- basophil
