Description of Antibodies
When the body is exposed to a pathogen, like a virus, the immune system creates antibodies against the pathogen. Those antibodies stay in the blood. The next time the body is exposed to that pathogen, the antibodies attack it before it can make us sick. It is as if the body sends out an all points bulletin, alerting the immune system to be on the lookout for specific pathogens. When those pathogens arrive, the immune activates antibodies to deal with the invader.
How Antibodies Form
The immune system has several different types of white blood cells, including B-lymphocytes. B-lymphocytes form in bone marrow and make antibodies. When a pathogen enters the body, the immune system triggers the B-lymphocytes to form antibodies specific to that pathogen. Once the pathogen is destroyed, the antibodies continue to live in the body, standing guard in case the pathogen returns.
Some pathogens reproduce by infecting body cells. With neutralization, antibodies bind with the pathogen and form antibody/pathogen complexes. These complexes incapacitate the pathogen by preventing it from communicating with other cells in the body. If the pathogen cannot communicate, it dies off. Imagine a computer system with a sophisticated firewall. The firewall detects an intrusion and closes the port before the virus or Trojan horse can invade the computer and communicate with the other files.
The immune system has specialized white blood cells called phagocytes. These cells are designed specifically to destroy and consume enemy cells. With opsonization, antibodies bind to the pathogen and release a chemical to attract the phagocytic cells. Imagine a guard dog (antibodies) cornering a burglar and barking to signal his location until someone arrives to take the burglar to jail.
Some antibodies perform double duty by binding and marking intruders and by activating complement. Complement is a chain of proteins that assist in destroying infected cells, viruses and bacteria. Imagine that the guard dog (antibodies) corners the burglar and signals his location. The security guard (complement) arrives on the scene and handcuffs the burglar. Then, the police (phagocytes) arrive to take the burglar to jail.
When Antibodies Fail
The immune system is an amazingly intricate and efficient machine. However, there are times when the immune system can overreact and malfunction. In the case of autoimmune disease, the body creates antibodies against its own healthy cells. According to the National Library of Medicine, there are more than 80 types of autoimmune disease including lupus, scleroderma and Hashimoto's thyroiditis.