Antigens and antibodies are essentially at war with each other inside most human bodies. Antibodies, also known as immunoglobulins, are Y-shaped molecules found in the blood that fight against foreign substances known as antigens. Antigens are proteins or polysaccharides of bacteria, chemical, or virus that attack the immune system. They can also cause allergic reactions due to dander, food, or pollen.
Generally, antigens can also be life-threatening in blood transfusions and organ transplants. For example, if a patient receives a blood transfusion and his or her body treats the new blood as a foreign substance, the antibodies can severely attack the immune system. With organ transplants, the tissue cells of the transplant could be rejected by the immune system. In both examples, this could lead to a major infection or even death.
Not all foreign antigens are environmental. For example, cancer cells are antigens that develop within the body. If the immune system fails to remove or destroy these cancer cells, they could multiply by millions and severely attack the immune system. Antigens and antibodies fight each other over the mere survival of the human body.
In response to these foreign substances, the immune system produces B cells, which are proteins that manufacture antibodies to attack the antigens. B cells are white blood cells found in the stem cells of bone marrow. They eventually develop into plasma cells, which produce the antibodies.
To attack the most common antigens found in the body, the Y-shaped molecules allow different antibodies to attach themselves to different antigens. The Y-shaped molecules lock onto an antigen key and then wrap themselves around the antigen until it is destroyed – antigens and antibodies are mortal enemies, in a sense.
At the ends of the Y-shaped molecules are amino acids. Amino acids are proteins that help the antibodies to recognize the presence of antigens. Each antibody is created to match most antigens. Antigens and antibodies are numerous in the body – the body’s immune system is able to record and destroy over a million different antigens.
There are five different classes of antibodies: IgA, IgD, IgE, IgG, IgM. IgA antibodies are usually found in mucus, saliva, and tears. IgD antibodies are found in the tissue lining of the belly and the chest, but it’s not exactly clear what their main function is. IgE antibodies release histamines against such foreign substances as pollen, food, hay fever, and asthma.
IgG antibodies are the most common and widespread antibody. They protect the immune system from major infections and diseases. Also, they move between cells and blood to protect organs and skin. IgM antibodies are the first antibodies that move against any type of bacterial, chemical, fungal, or viral attack.