Complement activation pathways

Complement activation pathways are part of the immune system that help protect the body from infections. When a threat is detected, these pathways activate a series of proteins that work together to mark invaders for destruction, attract immune cells to the site, and directly kill bacteria or viruses. There are three main pathways—classical, lectin, and alternative—that start differently but all lead to the same goal of defending the body. This system acts quickly and efficiently to help clear infections and support immune response.