First, how do antibodies relate to our immune system?

Throughout history, humans have been able to cope with numerous infections due in part to our body’s natural ability to create antibodies. Since antibodies play an important role in keeping us healthy, a common question arises: How long do they remain in our system?

First and foremost, we need to understand not only what an antibody is but how it relates to our immune system.

What Is an Antibody?

An antibody, also known as an immunoglobin, is a protein produced by the immune system to combat pathogens such as bacteria and viruses. These foreign substances are detected due to the antigens, or structures, found on them. For example, some components of a flu virus will alert the immune system to recognize it as “foreign” and begin creating antibodies to combat that virus. Antibodies, however, are not the only line of defense against infection.

Components of a flu virus will alert the immune system to recognize it as “foreign” and begin creating antibodies to combat that virus.

Our immune system is comprised of two levels of immunity: specific and non-specific immunity. Non-specific immunity consists of the physical and chemical defenses such as our skin and the enzymes in our saliva. It is our body’s first line of defense against invaders. Specific immunity is our body’s targeted response to a specific invader that has compromised the first line of defense and poses further threat. Through specific immunity, two types of white blood cells that are important for fighting infections are made: B cells and T cells.

The production of antibodies more specifically stems from the B cells—a type of white blood cell produced in bone marrow. T cells are important as well; they are also produced in bone marrow and form types of themselves to either stimulate B cells to make antibodies or kill infections. Antibodies, though, are the most common and abundant form of specific response to an infection. In fact, there are five types of antibodies (IgM, IgD, IgG, IgA, and IgE) that are produced with each type providing specific roles and characteristics for our protection.

How Long Do Antibodies Remain in Your System?

The specific lifespan of antibodies differs from each type of antibody, the individual involved, and the infection involved. Certain individuals may have conditions that affect the production of antibodies, but the two main types of antibodies that are initially produced in an infection are IgM and IgG antibodies. IgM antibodies are the first antibodies that are created usually after the first two weeks upon infection and have shorter lifespans than IgG antibodies. They are the acute response to the infection and findings of these in an antibody test may suggest that an individual has an active or recent infection for the disease tested for. Typically, after the initial phase and threat of infection, specific IgG antibodies are made several weeks later. These IgG antibodies are specifically made to combat that infection and remains in your system to help protect you from it in the future. These IgG antibodies can remain in the body ranging from weeks to years depending on the infection and person involved, so, knowing the exact time frame that these antibodies remain in the body can be unclear and unique to different pathogens.

The specific lifespan of antibodies differs from each type of antibody, the individual involved, and the infection involved.

For example, the common flu reappears due to the constant mutations the virus undergoes. Even though lgG antibodies are created for one type of the virus, it does not recognize the mutated type which then causes recurring sickness. You can even have pathogens that have unique abilities that allow them to evade or subvert antibodies or other defenses.

The common flu reappears due to the constant mutations the virus undergoes.

We get estimations of antibody lifespans by analyzing people that have been infected by a specific pathogen in the past. For instance, in a study involving people who were infected with West Nile Virus (WNV), it was found that nine out of the ten individuals tested had WNV lgG antibodies three years after initial infection. Studies like this can give us insight on how resilient our bodies can possibly be to different diseases. However, long-term immunity also stems from the aforementioned B cells as well.

When B cells produce antibodies, they also make what are called memory B cells that are made for a particular pathogen. These specialized memory B cells are designed to identify the familiarized pathogen in the future and more quickly create the specific antibodies to neutralize them more efficiently. Depending on the disease, these memory b cells have the potential to remain in the body for a lifetime, as seen in a study by co-author Dr. Eric Altschuler of the University of Medicine and Dentistry of New Jersey. In the study, blood samples from survivors of the deadly 1918 flu were taken 90 years after their encounter with the virus—it was found that they still had viable memory B cells that were able to create antibodies that successfully neutralizes it. For this specific flu virus, we may postulate that our bodies have the ability for long-term immunity for possibly decades.

Blood samples from survivors of the deadly 1918 flu were taken 90 years after their encounter with the virus—it was found that they still had viable memory B cells that were able to create antibodies that successfully neutralizes it.

Our bodies truly have a myriad of capabilities to protect us from the threat of infections. Antibodies are a vital component to our defense but understanding them and the intricacies of our immune system response, especially to acquired specific infections, is the resolution to learning the lifespan of the antibodies we produce.