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 ...

A new analysis of lung epithelial cells from COVID-19 patients reveals how the protective complement branch of the immune system, which usually plays roles in both innate and adaptive immunity, can ...

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 ...

Complement 3 glomerulopathy (C3G) is a rare kidney disease that affects your body’s innate immune system (complement system). Complement 3 glomerulopathy (C3G) is a kidney disease that’s caused by ...