| A | B |
|---|
| C1 | recognition unit of classical pathway |
| C4b2a | C3 convertase |
| C4b2a3b | C5 convertase aka activation unit |
| C5b6789 | Membrane Attack Complex |
| C5a | chemotaxin |
| C3a, C4a, C5a | anaphylatoxins |
| C3b, C4b | opsonins |
| Mannose-Binding Lectin (MBL) | recognition unit of lectin pathway |
| Mannose | activator of lectin pathway |
| lipopolysaccharide on bacteria cell wall | activator of alternative pathway |
| IgM or IgG bound to antigen | activator of classical pathway |
