You are here
Antibodies
Antibodies are complex proteins that are part of the blood. They intervene in the immune system (the body’s defence system). They are secreted by plasmocytes (components derived from white blood cells or B lymphocytes) in reaction to the introduction of foreign elements in the body.
These foreign elements are composed of small (most usually peptidic: small proteins of about ten amine acids) elements called antigens recognised by the antibodies and against which they react. The human body contains several billion antibodies. A virus, bacteria, fungi, parasite, venom, poison, vaccine, a cancer cell, etc. can therefore be recognised by the antibodies as noxious elements to be eliminated.
Antibodies react against the antigen that caused their secretion. They fix specifically to this antigen and mobilise other components of the immune system to neutralise and eliminate it from the organism.
Antibodies are often represented by a Y. They are composed of identical parts for all the antibodies of the same organism and variable parts. The variable parts allow recognising foreign bodies and are located at the end of the arms of the Y. They permit an adapted and targeted immune action. An antibody cannot fix to the antigen that caused its secretion except in specific cases of molecular mimetism.
The immune system is able to distinguish undesirable foreign elements from the elements making up the organism, except for cases of auto-immune diseases (the organism comes under attack by its own immune system).
Antibodies are used in medicine to prevent or treat certain diseases like tetanus, chicken pox, some types of hepatitis, scarlet fever, mumps, etc.