Complete action of complement enzymes in immune reactions can be studied in three phases.
1. Recognition and activation phase:
The first stage is recognition and activation phase. In this phase components of complement system recognize cell bound antibodies or antibody in immune complex and get activated.
2. Enzymatic phase:
Enzymatic phase is characterized by amplification of complement enzymes.
3. Attack phase:
Attack phase shows the formation of membrane bound complement complex (MAC) for attack on the target cell.