immune system response

What Is The Role Of IgG In Immune Response?

Each cell, protein, vitamin and nutrient in the body plays a role in how well the immune system functions, as well as the way it regulates and maintains its power to fight off harmful pathogens. Key cells and proteins that work together within the immune system include cytokines, lymphocytes, neutrophils, macrophages, complement proteins, and antibodies.

Antibodies, in particular, have special roles to play when it comes to your immunity. There are five in total, each serving a specific purpose. IgM antibodies, for example, are produced to hunt pathogens and mark them for destruction. The IgE antibody was recently found to have a role in allergies and the response of the immune system when an allergen enters the system. Certain lymphocytes called B cells rely on IgD to help produce new antibodies, and IgA is found in serum, nasal discharge, saliva, and breast milk and plays a role in maternal immunity, among other things.

The most prevalent antibody, however, is IgG. It makes up over 70% of all antibodies found in the system and is the only one that can pass through placenta, essentially protecting newborns in the womb and for a week after birth. It protects the body as a whole after being transported to blood and tissue. But what is the role of IgG in immune response, exactly?

What is the role of IgG in the immune system?

Aside from the aforementioned role of helping unborn children stay protected against pathogens, the role of IgG in the immune system is a large one. This is because it is the most predominant antibody. Its main job is to control any infections that may occur in bodily tissue, and it has the ability to bind to viruses, bacteria, and fungi.

It does more than just initial protection, though. IgG antibodies are able to memorize certain pathogens after binding to them. Because of this, these antibodies give the immune system a recall ability. For instance, if you come into contact with the borrelia bacteria, which causes Lyme disease, IgG antibodies will remember the pathogen so that if you come into contact with it again, the body can mass-produce the right pathogen-fighters so the infection can be tackled effectively.

tick on leaf
Image by Flash Dantz on Unsplash: The borrelia bacteria is transmitted by infected ticks, and the IgG antibody is key in warding off the Lyme infection it causes.

IgGs also have the ability to neutralize certain toxins and other pathogens, as well as activate the complement system – the part of the immune system that increases antibody and phagocytic cell ability. This essentially helps them clear out damaged cells, promote inflammation, and attack pathogens.

How long does it take to develop IgG antibodies to Lyme disease?

During the initial onset of Lyme disease, a different type of antibody is activated first to help seek out the bacteria in the body. Known as IgM, this antibody marks the bacteria cells for other immune cells to easily find and destroy. This occurs within the first few weeks of infection.

IgG antibodies are a little different. Because they are slower to develop after Lyme bacteria enters the system, it can take roughly four to six weeks for IgG antibodies to develop. In the four to six months following initial exposure to the Lyme disease bacteria, IgG antibodies will likely be at their highest within the body. These types of antibodies are associated with long-term protection because of their ability to stay active in the blood for many years. 

What does positive Lyme IgG mean?

Getting tested for Lyme disease generally requires two steps. In the event that the infection is still active, they will likely be tested for IgM antibodies, because these are at their highest during an active infection. That is not the case with IgG. If you were to get tested for Lyme disease and the test came back positive for levels of Lyme IgG, it simply means that you were infected by the pathogen some time in the past.

person testing in lab
Image by CDC on Unsplash: IgG antibodies can stay in your system for up to 20 years.

How long does Lyme IgG stay positive?

Although the exact length of time IgG Lyme disease antibodies will stay in the system is unclear, some research suggests that the antibodies can remain in the body for up to two decades following the initial infection. This indefinite timeline can be useful when testing whether a person has ever had Lyme disease, but it’s unlikely that they will be able to tell exactly when they were infected if a Lyme IgG test is positive.

IgG antibodies are vital to the immune response and proper protection against pathogens, especially since it’s so easy to come into contact with the same type of infection on multiple occasions. By providing long-term protection against specified pathogens, IgG antibodies are crucial in the overall health of the immune system and the response it launches to fight off disease and illness.

Featured image by Bru-nO on Pixabay

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