Antibody

Antibody - a protein produced in the blood which destroys bacteria, viruses and other substances that inter the body.
 

Antibody is a type of protein. The body's immune system produces antibodies when it detects harmful substances, called antigens. Examples of antigens include microorganisms (such as as bacteria, fungi, parasites, and viruses) and chemicals. Each type of antibody is unique and defends the body against one specific type of antigen. Antibodies are complex, Y-shaped protein molecules. The immune system's B lymphocytes, which are produced by the bone marrow, develop into plasma cells that can generate a huge variety of antibodies, each one capable of combining with and destroying an antigen, a foreign molecule. Antibodies react to very specific characteristics of different antigens, binding them to the top ends of their Y formation. Once the antibody and antigen combine, the antibodies deactivate the antigen or lead it to macrophages(a kind of white blood cell) that ingest and destroy it. High numbers of a particular antibody may persist for months after an invasion, eventually diminishing. However, the B cells can quickly manufacture more of the same antibody if exposure to the antigen recurs. Vaccines work by "training" B cells to recognize and react quickly to potential disease molecules.