An antibody, or immunoglobulins, is our natural defense against bacteria and viruses. They are Y-shaped protein that tag and stop infected cells from attacking other parts of the immune system. Simplified, there are two functions of antibodies: they are our immune system’s identifiers and neutralizers.
Antibodies are produced by the humoral immune system, and there are five types. Each type are distributed in different parts of the body; one may have a higher concentration in some parts. Antibodies also have different functions according to classification but they have the same method in destroying microbes – through a binding mechanism. In this article, we shall discover more about the types and functions of antibodies to gain a better understanding of their participation in our immune system.
The first in our list of types of antibodies is IgG. It makes up about 75% of all antibodies present in our blood and body fluids. The presence of pathogens, however, do not trigger the production of IgG. They are released a month after the white blood cells produce an antibody called B-cell. With this delay, their main role in the human immune system becomes more of a binder to form antigen-antibody complexes. This complexes make the pathogens much weaker, allowing other immune cells to destroy them easily.
The IgG is also responsible for activating a series of reactions between proteins to form a molecule that can perform the same function of an antibody. These molecules will become a part of the complement system to support the functions of the immune system. The capability of the IgG to permeate the placental barrier also makes it the only antibody to protect a developing fetus from pathogens.
The gut, the respiratory tract, and the urogenital tract are what we call mucosal areas – areas which are vulnerable to pathogenic attack. This is where IgA comes in. This type of antibody protects these mucosal areas from microbes and works to give them immunity from infection.
If the IgG is responsible for protecting a developing fetus, the IgA also plays a vital role in protecting a newborn child. IgA is secreted in breast milk to provide infants with passive immunity to microbes encountered by the mother. IgA is also secreted in saliva and tears.
IgE is an isotope that strengthens our immune response against parasitic worms. Its ability to trigger granulocytes also helps stop allergic reactions from spreading in the body. These allergic reactions may be caused by an animal or plant species such as dust mites, pollen and cat dander.
Through IgE, strong allergic reactions and massive inflammation can be prevented. However, there are still some people that are more prone to allergies than others; this disparity is discussed until today. Studies suggest that a mixture of genetics and the environment are two of the most common factors.
Another one of the types of antibodies is IgD, a receptor to cells not yet activated by antigens. Its only known function is to provide signals to mature B cells in the spleen. Apart from this, the role of this antibody has not been thoroughly explored.
The IgM is activated early on in the immune response, before the secretion of IgG. It is an isotope found on the surface of B cells or secreted by other cells. The IgM almost has a similar function with IgG; it also triggers the production of a complement system. However, it has been discovered that IgM is much more efficient than the IgG. Multiple IgG-antigen complexes are required to trigger the cascade, whereas it only takes one single IgM-antigen complex to perform the same function.