An immunoglobulin, or antibody, is a protein that is
released due to a response from the immune system when a pathogen, known as an
antigen, is found in the blood or other bodily fluids. There are five primary isotypes
of immunoglobulin in the human body and in other vertebrates. These antibodies
respond to threats by being released by white blood cells and then adhering to
a corresponding antigen which is then immobilized and neutralized to keep the
Immunoglobulins are proteins that are secreted at various sites around the body
to protect it from harmful particles known as antigens. This term includes
bacteria and viruses that could pose harm to the human body. When a potential
threat is perceived, the antibody that is first produced is immunoglobulin M as
it is the largest antibody and it is able to combat numerous antigens. Each
immunoglobulin is located at different locations in the body and carries out
its duties in an individual manner.
Immunoglobulin G presents the highest concentration of immunoglobulin in the human body than the other antibody isotypes. Due to this high accumulation, it is able to fend off more antigens and harmful particles than the other antibodies. There are several subtypes of immunoglobulin G within the human body and their delineation is based on their individual concentration. This antibody is also spread to a woman's fetus during pregnancy as it is able to safely cross the placenta.
Immunoglobulin A is found in the mucosal sites of the human body in higher concentrations than it is found in the blood or other bodily fluids. In its secretory form, this antibody is able to prevent antigens and pathogens from spreading infection through the mucous membranes and other sites. Immunoglobulin A can also be spread to infants through a mother's breast milk as this antibody is commonly found in the breasts prior to and after pregnancy.
Immunoglobulin E constitutes the smallest concentration of immunoglobulin in the human body. Despite its low amounts, it is able to catalyze powerful reactions in the body in response to antigens and other particles that may cause harm. Specifically, immunoglobulin E triggers a histamine response when allergens have been found in the body as a part of a person's natural response, or hypersensitivity, to allergens. As a result, many people are prescribed anti-histamines to prevent this from happening.