Complement system activation

The complement system is a part of the immune system that helps the body fight infections and clear damaged cells. It consists of a group of proteins in the blood that, when activated, work together to identify and eliminate pathogens like bacteria and viruses. Activation can occur through three pathways: classical (triggered by antibodies), lectin (triggered by sugars on pathogens), and alternative (spontaneous activation). Once activated, these proteins can destroy pathogens directly, mark them for removal by immune cells, or enhance inflammation to recruit more immune defense, ultimately protecting the body from harm.