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.

It was called ‘complement’ because it aided the antibacterial activity of antibodies. However, it is now known that the complement system can be activated early in an infection without the presence of ...

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 ...

Serotype M1 group A Streptococcus strains cause epidemic waves of human infections long thought to be mono- or pauciclonal. The gene encoding an extracellular group A Streptococcus protein ...