The body’s first line of defense is the immune system. When pathogens enter the body, cells within the immune system target them to help the body fight them off and avoid illness. There are three categories of immune cells: lymphocytes, neutrophils, and monocytes/macrophages. Each group of cells has its own respective tasks to do when the body is fighting off an invader.
The immune system also contains certain proteins that help protect the body even further. These include cytokines, complement proteins, and antibodies. Antibodies, in particular, are tasked with hunting down viruses, bacteria, fungi and other pathogens so they can mark them for other cells to find and destroy. Essentially, antibodies are the hunters of the immune system.
There are five types of antibodies that work for the immune system’s search-and-destroy task force, so to speak. Below, we’ll discuss two specific types: IgM and IgG.
What are the roles of IgM and IgG?
The main role of all antibodies is to seek out and mark pathogens to be killed or destroyed, but each antibody has its own division within the body that it needs to focus on. IgG and IgM antibodies are the types the circulate throughout the bloodstream and make their way into organs.
IgM antibodies are on the frontlines in the sense that they are produced first to provide fast but short-lived protection against illness. These types of antibodies are also an important part of immune regulation, as well as immunological tolerance. They can elicit different responses within the body by binding to antigens, setting in motion the attempts at fighting off invaders.
IgG antibodies are the types with memory on their side. IgGs have the ability to recognize certain pathogens. They are retained within the body and can be reproduced quickly if the body is ever invaded by the same pathogen again. They are tasked with the long-term protection of your health.
What is the difference between Lyme IgG and IgM?
When a person contracts Lyme disease, both IgG and IgM antibodies respond accordingly. The bacterial infection causes the immune system to ramp up, and this begins with the release of IgM antibodies. They are the first to seek out the source of the infection. During an active infection, IgM antibodies can be found in larger numbers, which can help indicate a recent or current infection with Lyme disease. However, since these antibodies slowly decrease over the weeks following the infection, it is difficult to determine a previous Lyme disease infection using IgM antibodies.
IgG antibodies, on the other hand, are there for the long-term. Once produced, these antibodies stick around and are likely to be found in the blood even after the infection has passed. In some cases, a negative test of Lyme disease IgM antibodies can lead to a positive test of IgG antibodies.
At what stages of Lyme disease are the IgG and IgM antibodies elevated?
Since IgM antibodies are created quickly after a pathogen enters the body, the numbers of IgM bodies during an active Lyme disease infection would be highest within the first few weeks of infection. During this time, which is referred to as early localized Lyme disease, IgM antibodies will begin to build up and hunt down the bacteria causing the infection. An early localized Lyme disease infection typically lasts anywhere from one to four weeks, with IgM antibodies being highest during the first several weeks before declining.
IgG antibodies begin production as IgM declines. These antibodies can still appear during the early localized state of Lyme disease, rising a few weeks following the onset of the infection. They then decrease, the same way that IgM antibodies do. However, they end up stabilizing during the course of the infection. This can happen during early localized Lyme disease, but the number of IgG antibodies will still be high enough to detect in a Lyme disease test during the second stage of Lyme disease, known as early disseminated infection, which can last up to four months.
How long do Lyme IgM antibodies last?
As mentioned above, IgM antibodies are not long-lasting. They are typically only produced at the beginning of an infection and slowly decrease in the few weeks that follow. They act as short-term protection, jump-starting the body’s defences against Lyme disease. This is why using IgM as a base when testing for Lyme disease will only help if the person has an active infection.
Although both IgM and IgG antibodies are needed to respond to certain infection-driven illnesses, they do so in their own ways that benefit the health of the body in both the short term and long term.
Featured image by Kelly Sikkema on Unsplash
