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 complement blood test checks for autoimmune diseases or other issues with your immune system. Your doctor might test you if you have a family history of certain conditions, such as rheumatoid ...

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 ...

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 ...

Faults in a certain part of the immune system might be at the root of some long covid cases, new research suggests. For many people, covid is an illness that blusters in and out of our lives as cases ...

Researchers at Penn Medicine have discovered a new, more effective method of preventing the body’s own proteins from treating nanomedicines like foreign invaders, by covering the nanoparticles with a ...