L9:Complement system and activation Flashcards
where are compliment serum proteins formed ?
liver
which pathway is important for adaptive immunity ?
classical pathway
what pathways are important for innate immunity ?
alternative and lecin pathways
what are the functions of compliment pathways ?
cell lysis by action of Major attack complex
opsonization of bacteria
generation of inflammatory mediators
what is the central molecule of all pathways ?
C3b
how is the classical pathway activated ?
antibody-antigen complex
c3 convertase in classical pathway is comprised of ?
C4b2b
what does C3a do?
activates mast cells causing rleases of vasoactive mediators like histamine
what does c5 convertase consist of ?
C4b,2b,3b
what does C5a do?
it is a pro-inflammatory anaphyltoxin and a chemotaxin
what is the major attack complex ?
C5b,6,7,8,9
how is the alternative pathway activated ?
there is NO antigen-antibody complex in the alternative pathway . instead , the pathway is activated when c3(h20) binds with B factor which has been cleaved by protease and factor D.
It is activated when C3b binds to any activator or microbial surface
how is factor b cleaved in the alternative pathway ?
by protease and factor D
how is the lecin pathway activated ?
when MBL or MBP bind to surface bearing mannose or mannon , which activates MBL associated serine proteases which in turn activates c4 and c2 to form c3 convertase
which pathway doesnt have c2 and c4?
alternative pathway
what does c3b binding to surface of B cells do?
enhances antibody production
which compliment serum proteins are chemotaxinsn ?
c5a , c5,6,7
which compliment serum proteins are anaphylotoxins ?
c3a ,c4a ,c5a , they cause degranulation of mast cells with release of histamine ( pro-inflammatory ) causing increased vascular permiability and smooth muscle contraction ( especially bronchioles causing branchospasms )
