The Complement System

Complement

A group of molecules that causes cytolysis

C1

Recognition Unit

Q, R, and S

Subunit of C1

C4, C2, C3

Activation Units

C5, C6, C7

Membrane Attack Units

C8, C9

Final Membrane Attack Units

Opsonins:

enhances phagocytosis

Chemotaxins

Influences WBC migration towards site of injury,

infection or inflammation

Classical Pathway

Activated by Ag-AB complex.

Alternative Pathway

Activated by Microbial Polysaccharides (LPS of gram neg

bacteria)

Lectin Pathway

Activated by Carbihydrate-rich surfaces

MASP1 and MASP2

MBL activates this two stimulants.

C4b2a

C3 Convertase compound

C4b2a3b

C5 Convertase compound

C4

MASP 1 activates this

C2

MASP 2 activates

C2b, C3a, C4a

Complement released into the blood circulation and will

become either a chemotaxin, opsonin or anaphylatoxin