Complement control protein

The complement system distinguishes "self" from "non-self" via a range of specialized cell-surface and soluble proteins. These homologous proteins belong to a family called the "regulators of complement activation (RCA)" or "complement control proteins (CCP)". Complement control proteins work in concert to regulate the system and keep it from damaging host tissue while simultaneously directing it towards foreign particles such as viruses and bacteria, and unwanted material such as cell debris and antibody-antigen complexes.