A complement C4 (also known as a complement component 4, or simply C4) is a test to measure the level of C4 proteins you have in your blood. These proteins play a role in how your immune system ...

Your complement system consists of a group of important proteins in your bloodstream. These proteins help your immune system fight off harmful invaders, such as bacteria, and other foreign substances.

Please provide your email address to receive an email when new articles are posted on . A protein known as granzyme K was recently shown to be a driver of inflammation by activating the complement ...

Global understanding of complement has shifted and developed since the 21st century: from our idea of a blood-based antibiotic system to a global regulator of immunity and tissue homeostasis. Recent ...