The correct answer is: Formation of the MAC in invading cells, killing them
The complement pathway or system is a part of the innate immune system that helps antibodies and phagocytic cells to clear microbes and damaged cells from an organism. Its role is to enhance and promote inflammation, and to attack pathogen's cell membrane. The complement system consists of a number of small proteins and as a result of their activation these are the mechanisms of action:
• stimulation of phagocytes
• inflammation to attract more phagocytes,
• activation of the cell-killing membrane attack complex (MAC).
