Complement Flashcards
Complement Receptor 1 is expressed on what class of cells?
Phagocytes
Opsonization is accomplished by what 4 complement proteins?
C1q, MBL, C4b, C3b
CR1 binds which osponins?
C4b and C3b
Which 3 complement proteins are key to promoting inflammation?
C4a, C3a, C5a
The inflammatory subunits C3a, C4a, and C5a all belong to what group of small molecules?
Anaphylatoxins
What effect does C5a have on phagocytes?
Increases CR1 expression and thus increases phagocytosis
Anaphylatoxins also trigger the degranulation of which cells?
Basophils, eosinophils, neutrophils, mast cells
What complement protein is important in immune complex clearance?
C3b
During the process of immune complex clearance, what does C3b bind?
Ag-Ab complex + CR1 of erythrocytes
What is the role of C3d?
Enhances B cell activation by binding the BCR-Ag complex + the coreceptor CD21 (CR2)
What are two ways microbes evade the complement system?
Interference with antibody-complement interaction, and binding and inactivation of complement proteins
What does C1q activate?
C1r
What does C1r cleave?
C1s
What does C1s cleave?
C4 and C2
Which subunits comprise the C3 convertase?
C4b2a
C3 convertase cleaves?
C3
C3b binds to what?
The C3 convertase (C4b2a)
What is the C5 convertase composed of?
C4b2a3b
What pathway includes the spontaneous hydrolysis of C3?
The Tickover pathway (alternative pathway)
What activates the alternative pathway?
PAMPs
What binds the hydrolyzed C3b?
Factor B, yielding C3bB
Factor D does what?
Cleaves Factor B, resulting in C3bBb
C3bBb is what enzyme in the alternative pathway?
The c3 convertase
What is the role of prosperdin?
Stabilizes the C3 convertase (C3bBb)
What does the C3 convertase produce?
C3b and C3a
What does some of the produced C3b then do?
Binds the C3 convertase, resulting in the C3bBb3b enzyme (C5 convertase)
What is a lectin?
Protein that binds a carbohydrate
