Complement Flashcards
Classical pathway order
1r/q/s, 4, 2, 3, 5, 6/7/8/9
- C6,7,8 and 9 bind to the activated C5, forming the membrane attack complex
- C 8 is the one that first inserts itself into the membrane
- C9 polymerizes and forms a pore on the membrane surface
- creates lesions which kill the cell via a inrush of fluids
opsinization and complement
coating of organisms with antibody and C3b so that they are more easily phagocytosed by neutrophils and macrophages (can do it alone but is much slower)
chemotaxis in completment
- C3a and C5a
- phagocytic cels are attracted to the site of the antigen
anaphylatoxin production and complement
- C3a and C5a degranulate mast cells and basophils
- granules contain potent inflammatory chemicals eg histamine
lysis of organsims and complement
-coated with specific antibody and recruit C8 and C9
inhibitor of the classical complement pathway
-C1-inhibitor
alternative complement pathway
- how is it activated
- proteins involved
- by bacterial or viral products (LPS)
- proteins involved: C3b, factor B and D, properdin
- together generate C3bBbP which splits c3 into C3 and Cb and continues the the classical cascade
inhibitors of the alternative pathways
-Factor H and Factor I are inhiibitors of the alternative pathway and regulate the activation of the system
lectin pathway
- activated by organisms with mannose on their surface
- proteins involved: MBL (mannose binding lectin), MASP1, MASP2, C4, C2
- C4b2b cleave C3 and this cascade enters the classical pathway
absence of C1q, C2, or C4
-associated with SLE
absence of C3
-severe recurrent bacterial infection
absence of C5
-bacterial infection
absence of C6,7,8
overwhelming neisserial infection
absence of alternative pathway components
-recurrent bacterial infections
absence of lectin pathway proteins
-infection in childhood
