What Are Antibodies?

An antibody is a protein produced by the immune system. It is created when the body detects foreign substances through antigens. An antigen can be a number of things, including a protein or a sugar. They exist on bacteria, viruses, parasites, tumor cells, and normal cells. 

The antigen functions like a nametag—your immune system reads the name tag and checks the guest list to see if it belongs. The cells and proteins in your body have “self-antigens,” and if the antigen does not belong (“non-self”), antibodies are called into action.

Antibodies are produced by B cells, which are a type of white blood cell. When a B cell spots a foreign antigen, it begins to form into a plasma cell. That plasma cell then releases millions of antibodies specific to that antigen.

Our understanding of antibodies began in 1890 when Emil von Behring and Shibasaburo Kitasato showed that serum from an animal infected with diphtheria could help treat and prevent infection in other animals, the first instance of a vaccine. Their work went on to win a Nobel prize in 1901.

Since then, we have learned that there are 5 different types of antibodies, which are separated by their structure, their function, and the location where they are found.

• IgA: found in tears, saliva, breast milk, mucus, and intestinal fluids. Protects against inhaled and ingested pathogens.
• IgD: found on the surface of B cells. May support B cell activation and maturation.
• IgE: found primarily in the skin, mucous membranes, and blood vessels. Causes mast cells (another type of white blood cell) to release histamine.
• IgG: the most common antibody, found in blood and tissue fluids. Helps protect the body from bacterial and viral infections.
• IgM: found in the lymph system and blood. The first line of defense against infections and helps with immune regulation. 

Furthermore, the various antibodies differ in structure. Antibodies consists of Y-shaped units. The tips of the “Y” have an amino acid sequence matching a specific antigen, so it can attach to it more easily. This allows the antibody to directly target the foreign antigen and remove it from the body.

Can You Detect Antibodies?

Knowing how important antibodies are for our immune system, how can you check if you have them for a specific disease?

Antibodies are detected through antibody serology testing, a type of blood test. It may also be called an antibody titer test or simply a titer test.

In an antibody test, blood is drawn and then centrifuged, i.e. placed in a special device that rotates very quickly. This causes the blood to clot and settle. What remains on top is the blood serum and is used for the antibody test. The serum is then sucked through another device and mixed with antigens or whole viruses. If you have antibodies for the disease in question, they recognise the antigens and bind to them.

Common Uses of Titers

Since a titer is a laboratory test that measures the presence and amount of antibodies in the blood, it can help, together with the patient's medical history, to assess their immunity to a disease.

An antibody level above the disease-specific threshold is used as an indicator of sufficient immunity against the disease. However, antibody titer testing is no hard proof of sufficient or insufficient immunity, as it only reflects one of many parts of the immune system.

A titer antibody test may be ordered to determine the following:

• Whether you recently had or currently have an infection
• Whether an immunization triggered a strong enough response in the body
• If you need a booster shot
• Whether you have elevated antibody titers against humanoid tissues (your own tissues), which could indicate an autoimmune disoder

Using Antibody Testing to Identify Who Needs a Booster Vaccine

One application of antibody testing is to gauge your body’s immunity to a specific disease. 

While there are other elements to your immune system beyond antibodies, knowing that you have low antibody levels for a specific disease may be a sign that you were never vaccinated, or that it is time for a booster vaccine, which reintroduces the antigen into your body so that you can produce more antibodies. However, an antibody test to determine whether a booster is necessary is only indicated in certain cases.

For those who may not respond well to vaccines, an antibody test can provide useful information regarding the presence and level of antibodies.

Thanks to antibody testing, you can better understand what is going on inside your body and optimize your health strategy.

Schedule a Routine Vaccination Check

Antibodies are a crucial component of our immune system, but they only develop once your body has been exposed to a disease. This can occur in two ways: through an infection or through a vaccine. Since a vaccine utilizes a weakened or dead form of the illness—keeping you from getting sick with the illness itself—it is the safer option.

However, not all vaccines last your whole life—some require boosters every few years. The purpose of these boosters is to reintroduce the virus and increase your antibody levels again.

If you’re not sure whether your vaccinations are up to date, please book an appointment for a “routine vaccination check,” where we will complete a full assessment of your records, comparing your vaccination status with Switzerland’s recommendations. 

References

Explaining How Vaccines Work. (2023). Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/hcp/conversations/understanding-vacc-work.html

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COVID-19 Serology Testing Explained (2020). ASM.org. https://asm.org/articles/2020/may/covid-19-serology-testing-explained

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Aziz M, Iheanacho F, Hashmi MF. Physiology, Antibody. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546670/

Functions of Antibodies. (2014). Microbiology Spectrum. https://journals.asm.org/doi/full/10.1128/microbiolspec.aid-0019-2014