Human Antibodies: Quantity, Function & Immune System Role

There are an estimated 100 trillion antibodies in the human body. Antibodies are proteins that are produced by the immune system to fight infection. They are found in the blood and other body fluids, and they work by attaching to antigens, which are foreign substances that can cause disease. When an antibody attaches to an antigen, it triggers the immune system to destroy the antigen.