• Question: Once your body creates antibodies for a disease, can time end up ‘killing’ those antibodies and therefore making you again vulnerable to that disease or do those antibodies ‘stay’ in your body forever?

    Asked by anon-256593 on 8 Jun 2020.
    • Photo: Olivia Edwards

      Olivia Edwards answered on 8 Jun 2020:

      Interesting question! When an individual is exposed to an infection, their immune system will produce antibodies which recognise the pathogen e.g. a virus, and help destroy it. The immune system should then produce ‘memory’ cells which will remain in the blood, and if the same pathogen comes back, will recognise and destroy it quickly.

      However, the quality and amount of antibodies produced by each individual can vary, and may be worse when the individual has a problem with their immune system. Over time the immune system often becomes weaker, and some of the memory cells can be lost. This might mean that in the future someone may not recognise an infection even if they have had it before. This can also happen when the pathogen changes a lot over time (by gaining mutations), if this happens a lot the memory cells may no longer be able to recognise the pathogen, and the person can become infected again.

    • Photo: Alicia Galdon

      Alicia Galdon answered on 8 Jun 2020:

      Hi Javier!
      Antibodies are made by a kind of immune cell called a ‘B cell’. When you get a new infection, B cells specific to that infection start producing lots of antibodies.The antibodies themselves do slowly start to die off over time, however the B cells that make them stay around and become what are known as ‘memory B cells’. These memory B cells can stay in the body for years, ready to make new antibodies if you come into contact with that infection again.

      We don’t know how long these memory B cells stay around for every disease. Some pathogens are much better are inducing memory B cells than others. For example, for most people, being exposed to measles just once is enough to give you immunity for your whole lifetime (memory B cells against have been found in the blood 80 years after being exposed!). For others, you need a couple of exposures to build up strong immunity. Some pathogens may not induce memory cells at all (though this much rarer). It’s also thought that the younger you are exposed to a disease, the better your immune system is at making long-lived memory cells, whereas elderly people have been found to make memory B cells that don’t last as long.

      Whilst these memory cells usually do a really good job at making sure we are protected against the disease, unfortunately its not always the case. Some people’s B cells can make antibodies that don’t work properly, or they might make not make enough antibodies. These people unfortunately will stay vulnerable to the disease.

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