Complement Flashcards
Deficiency in C1, C2, C4
immune-complex disease
Deficiency in C3
susceptibility to encapsulated bacteria
Deficiency in C5-C9
Susceptibility to Neisseria
Deficiency in factor D or properdin (factor P)
- susceptibility to encapsulated bacteria and Neisseria
- No immune-complex disease
immune complex
antibody binding to antigen
Deficiency in factor I
susceptibility to encapsulated bactera
How do deficiencies in C3 and Factor 1 happen?
have too much binding –> these factors get used up
Deficiency in DAF, CD59
Autoimmune-like conditions including paroxysmal nocturnal hemogobinuria
Deficiency in C1INH
hereditary angiodema (HAE)
What does a loss of early classical complement pathway components lead to? What doesn’t it lead to?
- leads to immune complex-like disease
- NOT increased rate of bacterial infections
- just can’t clear the complexes, but they form
C5a
most important complement component for mediating inflammation
opsonization
critical role of complement
terminal complement reaction
- cleavage of C3
- necessary to kill Neisseia bacteria
how are immune complexes cleared
complement
complement membrane attack complex
- C5-C9
- lysis of target cell after C3 has been cleaved
cleavage of C3 –>
- C3a recruits phagocytes
- C3b tags bacterium for destruction
in classical complement, what cleaves C3
C2a:C4b complex
CR1
phagocytosis
iC3Bb
soluble C3 convertase, initiates alternative pathway
chemoattractant complement protein
C5 (C5a)
alternative complement pathway
- properdin stabilizes C3bBb (C3 convertase) on pathogen surface
- factors H and I inactivate C3b –> iC3b
- DAF and MCP disrupt C3bBb (C3 convertase) on self cell surface
CR1 and CR3
CR1 on macrophage binds CR1 on bacterium
C3a, C5a
anaphylatoxin - histamine release for mast cells, increase vascular permeability
C5a
chemotaxis - attract polymorphonuclear leukocytes and macrophages
