Learn about the most highly produced antibody in our system, immunoglobulin A (IgA). Discover how IgA maneuvers into body cavities, acting as an important defense against bacteria and viruses.
When foreign bodies invade, our immune system has to act quickly. Luckily, it has a swarm of antibodies ready for the job. These antibodies are proteins specifically designed to attach to invaders like bacteria, viruses, and toxins. Antibodies are precisely designed to bind to specific invading proteins, or antigens, that the bacteria, viruses, or toxins display. There are five groups of antibodies that our system produces: immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin E (IgA), immunoglobulin M (IgM), and immunoglobulin D (IgD). Today we’re going to be focusing on IgA, but we’ll still be exploring some basic principles of immunoglobulins in general.
Basic IgA Structure
Imagine immunoglobulins shaped like a two-pronged fork, and using the tip of the fork to attach to a foreign antigen in order to disable it. This Y-shaped structure is shared among all classes of immunoglobulins, including IgA. It contains two identical heavy chains and two light chains. You’re right if you guessed that the heavy chain weighs more and is larger than the light chain. The heavy chain extends along the entire length of the Y structure, whereas the light chain binds to the heavy chain on the exterior of the prongs of the Y shape.
IgA Fights Disease
Secretory IgA is highly present in mucous membranes because these sites are easy targets for foreign invaders. This immunoglobulin is important for fighting common bacteria and viruses.
IgA is an effective fighter against bacteria like Salmonella, which initiates symptoms that include diarrhea, cramps, and fever. It also helps prevent cholera caused by the bacteria Vibrio cholera and fights Neisseria gonorrhoeae, which causes the STD gonorrhea. IgA is also known to be important for fighting viruses that cause polio, influenza, and reovirus.
Our body makes antibodies as a vital defense system against foreign bodies. There are five classes of antibodies, or immunoglobulins, that our body synthesizes: IgA, IgG, IgA, IgM, and IgD. With the help of a secretory component, IgA can transverse through cell membranes. Most of the IgA in our bodies is secretory IgA and travels to the fluids and mucus of exterior cavities.
Many viruses and bacteria that commonly enter our bodies through these cavities are bound and trapped by IgA, protecting us from infectious agents.