Complement Pathway Flashcards
Cleaves c1s to activate protease function
C1r
Binds to antibody that has bound antigen, activates C1r
C1q
Cleaves C2 and C4
C1s
Unknown function
C2a
Activate enzyme of classical pathway
Cleaves C3 and C5
C2b
Mediates inflammation
Anaphylatoxin
C3a
Binds c5 for cleavage of C2b
Binds cell surfaces for opsonization and activation of alternate pathway
C3b
Mediates inflammation
C4a
Binds C2 for cleavage by C1s
Bids cell surfaces for opsonization
C4b
Mediates inflammation, anaphylotoxin, chemotaxin
C5a
Initiates assembly of the membrane attack complex
C5b
Binds c5b
Forms receptor for c7
C6
Binds c5b6, inserts into membrane, forms acceptor for c8
C7
Binds c5b67
Initiates c9 polynerization
C8
Polymerizes around c5b678 to form channel that causes cell lysis
C9m
Alt Path
Mediates inflammation
Anaphylotoxin
C3a
Alt Path
Binds cell surfaces for opsonization and activation of alternate pathway
C3b
Alt Path
Bids membrane bound c3b
Cleaved by factor D
Factor B-B
Alt Path
Unknown
Factor B-Ba
Alt Path
Cleaved form stabilized by P produces c3 convertase
Factor B-Bb
Cleaves factor B when bound to c3b
Alt Path
Factor D
Binds and stabilizes membrane bound c3bBb
Alt Path
Properdin-P
Cleave C2 and C5
Lectin Pathway
MASP
Lectin pathway or
Mannose binding lectin pathway
Activates C1s
C1r
Binds to fc region of IgM and IgG
C1q
MASP
Cleaves c4 and c2
MASP 2
Central molecule of complement cascade
C3b
C3b functions
Opsonizes bacteria
Combines with other complement to generate c5 convertase
For opsonization
Enhance phagocytosis
C3b
C1q
For chemotaxis
Attracts neutrophils
C5a
C5, 6, 7 complex
Enhance adhesiveness of neutrophils to endothelium
C5a
Serves as chemoattractants for chemotaxis
C5a
Anaphylotoxin
Mast cell
Basophils
One of the agents that induces vascular permeability
Histamine
Disrupt membrane and entry of water and electrolytes into the cell
Cytolysis MAC
Binding of c3b to its receptors on the surface of activated B cells
Enhance ab production
Important regulator of classical pathway
C1 INH
Serine protease inhibitor/serpin
C1 INH
Irreversibly binds to and inactivates c1r and c1s as well as MASP in lectin pathway
C1 INH
Regulates alternative pathway
Factor H
Reduces amount of c5 convertase available
Factor H
Protects c3b and stabilizes c3 convertase
Properdin
Cleaves cell bound or fluid phase c3b and c4b
Inactivates c3b and c4b
Factor I
Glycoprotein on surface human cells
DAF
Prevents assembly of c3bBb or accelerates disassembly of preformed convertase
DAF
Cofactor of Factor I
C4b binding protein
C4BP
Inhibits the action of c4b in classical pathway
C4BP
Splits c4 convertase
C4BP
Protectin
CD59
Vitronectin
S protein
Inhibits formation of MAC by binding c5b678
Protectin and vitronectin
Present of self cells to prevent complement from damaging them
Protectin and vitronectin
Inhibits MAC formation
Homologous restriction factor
Proteolytically cleaves the anaphylotoxins
Anaphylotoxin inhibitor
Most severe complement deficiency
Deficiency of c3
Deficiency of c5-c8 and mannan binding lectin
Predispose to severe neisseria bacteremia
Deficiency of c1 to esterase inhibitor
Angioedema
Inc capillary permeability
Paroxysmal nocturnal hemoglobinuria dse
Marcha-fava Mitcheli syndrome
Only hemolytic anemia acquired
Paroxysmal nocturnal hemoglobinuria
Defect in intrinsic factor which os glycophosphatidyl inositol (red urine)
Paroxysmal nocturnal hemoglobinuria
Measures over all complement activity of classical and alternative pathway
CH50 and AH50
Measures total classical pathway
CH50