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.

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 ...

Complement component 3, often called C3, is an essential protein of the immune system. This protein plays a vital role in the body’s innate immune system, providing: the first line of defense against ...

We all forget things, and sometimes it would be better if we did not. Normal forgetting occurs more frequently as we age, but more serious, progressive, retrograde forgetting, which can have severe, ...

Complement proteins may be helpful when it comes to rallying clearance of hazardous debris from the brain, but scientists believe the immune activators can also inflict irreparable damage to neurons ...

These findings suggest complement protein levels may be an important biomarker for type 1 diabetes. Disruption of the complement system appears to precede the onset of islet autoimmunity (IA), making ...

This story was updated on February 5, 2019. Just when you thought ApoE biology couldn’t get any more complicated, scientists have discovered a new function for this apolipoprotein. According to a ...