Complement COPY Flashcards
consists of a group of around
40 proteins
which paper talks about complement
sousa 2011
where are complement proteins synthesised
the liver
main roles of complement
1) inflammation
2) opsonisation
3) Lysis
innate immunity kills…
bacteria, fungi, virus’ and parasites
main components of complement
C1-C9
complement proteins are named in
order that they were discovered, not the order that they act
cell lysis mediated by the
membrane attack complex…
name the three pathways
classical
lectin
alternative
complement and phagocytosis
phagocytes have complement recpetors- these receptors bind to pathogens opsonised with complement (C3b and C4b).
MAC formation
C5b bind sC6 and C6
- C5b67 complex binds to pathogen membrane via C7
- C8 binds to the complex and inserts into the cell membrane
- C9 molecules binds to the complex and polymerises
- 10-16 C9 molecules form a pore resulting in osmotic lysis and cell death
classical pathway activated by
antigen-antibody complies (IgG and IgM)
alternative pathway activated by
microbial survives e.g. polysaccharide
lectin pathway activated by
mannose-binding lectin
classical pathway activation occurs when
C1q/r/s molecule binds to Fc portion of Ab
binding of C1q/r/s causes
conformational change
conformational change to C1qrs
cleaves C1s to an active serum protease
C1s cleaves
C4 to C4a and C4b
C4b
cleaves C2 to C2a and C2b
C2a binds to
C4b
C4bC2a complex
C3 convertase
C3 converts
cleaves C3
C3 cleaved to … by C3 convertase
C3a and C3b
C3b, C5a and C5b
C5 convertasse
C5 converts cleaves C5 to
C5a and C5b
C3a and C5a
inflammation
C5a
chemoattractant for macrophage and neutrophils
C3a and C5a bind to
mast cells- cause them to degranulate- releasing histamines –> inflammation
C3b and C4b
opsonisation
MAC complex
lyse bacteria
- C5b binds with C6-9
- formation of large (10nm) pore
pore causes
water, ions and small molecules to enter the cell–> lysis
