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 ...

Complement is a key component of immunity with crucial inflammatory and opsonic properties; inappropriate activation of complement triggers or exacerbates inflammatory disease. Complement ...

When told what to kill, the complement system deftly deals the final blows—helping the immune system purge away pathogens and infected cells. But in the nervous system, debate rages as to whether this ...