Complement C4 Unit Converter

Complement C4 is one of nine major proteins (C1 through C9) that make up your complement system, an essential part of your innate immune defense.

The complement system works alongside antibodies and white blood cells to identify and destroy bacteria and viruses, clear away dead cells, and remove foreign material from the body.

C4 is specifically involved in the classical and lectin complement pathways, which are activated when the immune system recognizes certain microbes or antibody-antigen complexes.

C4 is produced primarily by the liver, with smaller amounts made by macrophages (a type of white blood cell) and tissues including the adrenal glands, thyroid, and kidneys.