Complement System Flashcards
Complement system
a group of serum proteins in the blood that persons a critical defence against pathogens
~ links to adaptive and innate IS
Name the 7 functional categories of complement proteins.
- Initiators
- Enzymes
- Opsonins
- Anaphylatoxins
- Membrane attack proteins
- Complement receptors
- Regulatory proteins
- Initiators
binds pathogens component or antibodies
Enzymes
convertases - protein activating enzymes
Opsonins
promote phagocytosis
Anaphylatoxins
cause inflammation
Membrane attack proteins
lyse pathogens
Complement receptors
on phagocytes or neutrophils
Regulatory proteins
limit complement activation
Name the three complement activation pathways.
- classical
- lectin
- alternative
Classical pathway is initiated by…
binding of antibodies (IgG and IgM) to the surface of a pathogen
Lectin pathway is initiated by…
lectins that bind to carbohydrates on the surface of pathogens
MBL
Mannose binding lectin:
binds mannose and other sugars on the surface of /Salmonella/, /Listeria/ and other bacteria
Alternative pathway is initiated by…
‘tickover pathway’ = low level of spontaneous binding of C3, generates C3b which is able to microbial surfaces
