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Multiple Sclerosis 101: Understanding the Immune System

Multiple Sclerosis 101: Understanding the Immune System

The immune system is a fascinating and complex thing! In fact, scientists still have a lot to learn about the immune system and autoimmune diseases. We know it plays a role in the development of multiple sclerosis, and in the damage of myelin that occurs in people with MS. This is why many disease modifying drugs used to treat MS work by manipulating our immune systems. Therefore I think it’s important to understand at least the basics of the immune system response, because it helps to explain what goes wrong in a person with an autoimmune disease such as MS.

A basic overview of how the immune system works

The immune system is the police patrol of the body, its job is to serve and protect you. It constantly works to defend you from foreign invaders that could do damage and/or threaten your life. White blood cell’s are like police officers out on foot patrol. They circulate in your blood stream, constantly scanning for trouble in the streets and looking for foreign invaders. Other cells have what are called antigens on their surfaces, which act kind of like a photo ID. The patrolling white blood cell’s can check this ID and tell which cells belong to you, and which do not. If they see a cell who’s ID doesn’t check out, they immediately handcuff it by engulfing it and calling for backup. At that point millions of immunologic cops come running to the fight. The foreign cell’s antigen is then chopped off and taken back to the lymph nodes for investigation.

Lymph nodes are the police precincts of the body, and the police captains are called the B and T cells. B and T cells are made in the bone marrow and mature in the spleen, thymus, and other tissues of the lymphatic system. Once they are alerted that there is a foreign invader they spring into action. The T cells migrate from the lymph nodes into your circulation to kill off any of your own cells that were infected during the immune response, and direct other cells to the scene of the crime. B cells take the foreign antigen that was seized, and use it to create a defensive weapon known as an antibody. An antibody is specifically designed by your immune system to kill off the particular foreign invader, or pathogen, that it was made from. The B cells then create drones covered in those antibodies and send them to hunt and kill off the pathogen. Interestingly, doctors have been using this principle to combat the Ebola outbreak. They are taking blood containing antibodies from people who have been exposed to Ebola, and transfusing it into others in an attempt to help their immune systems combat the virus. This obviously has nothing to do with MS, but I thought I would throw that in as an interesting example anyway!

Once your immune system is able to produce antibodies faster then the pathogen can replicate and invade your body, the infection is successfully defeated. The immune system has an excellent memory, and can remember which antibodies it needs to produce in order to attack certain targets. The second time our immune system encounters a specific pathogen, the antibodies created during the first exposure are rapidly produced again. This is much more efficient then having to create an entirely new weapon, so the immune response is faster and stronger during each subsequent exposure. Therefore, the immune system is often able to detect and suppress pathogens before they can make you sick.

What are autoimmune diseases?

In autoimmune diseases such as lupus, celiac’s disease, and multiple sclerosis, the immune system makes a mistake in reading the cell’s antigens (their ID) . It thinks that the body’s own cells are foreign invaders. The immune system the launches an attack against our own cells, like it is trained to do to foreign invaders.

There is a barrier between your circulatory system and your brain (aptly named the blood-brain-barrier), which normally keeps immune cells out of the delicate tissues of the brain. In multiple sclerosis immune cells make their way through a damaged blood brain barrier, attack oligodendrocytes (the cells that make myelin) and myelin, and cause central nervous system damage. There is still much we have yet to learn about why this process occurs in the first place, and the exact roll it plays in MS. But for now, the most effective method we have of preventing further damage is to use drugs that keep the immune system from mounting an attack on our own cells, and many of these medications work by suppressing the immune system.

What role do vaccines play?

Vaccines are a way of introducing either a weakened or a fake antigen into your body so that your immune system mounts a defense against pathogens like the measles, chickenpox, or the flu. That way if you are exposed to these diseases at some point in the future, your immune system will remember how to fight them, and use the antibodies from it’s arsenal to suppress the infection before it makes you sick.

Recommendations on which vaccines are safe for people with MS are updated periodically, so I always consult the National MS Society’s guidelines. You can find them here.

Those are the major principles of the immune response involved in MS. Anyone have any questions?

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.


  • jennyb
    3 years ago

    As a young person, probably when I wa 24 or so, I had Hodgkin’s Disease for the first time. It was a matter of course that they removed my spleen, which is part of the immunne system. I had no problem with that until years later, when I started getting diseases; psoraitc arthritis, (inherited from my dad) Menier’s Disease, MS, and a bunch of other things. I started calling them “disease dejour”. An oncologist told me recently that now days they don’t touch organs when treating cancer, and that splenectomy may be why I get so many auto immune diseases. Without the cancer treatment I received (minus the splenectomy) I would not be here to bitch about it. Oh well, we all do the best we can.

  • cw
    3 years ago

    Agree this is a good article on explaining autoimmune disorders. Is this why my lymph nodes are constantly swollen?

  • RebeccaK
    5 years ago

    Great article. The story explains it so clearly and really helped. I get confused about immune suppression. As I understand it, out immune systems are over-active so immune suppressant drugs slow it down. (I may completely misunderstand:)I just started Tysabri and they told me that it may weaken my immune system so it may be easier to get and fight infections. But it’s not an immune suppressant drug.??? And…given all the above, should one still boost the immune system with things such as vitamin C or does that exacerbate the problem? Thanks. RebeccaK

  • Stephanie Buxhoeveden, RN, MSCN author
    5 years ago

    Hello Rebecca!

    You are correct, our immune systems are over active which leads central nervous system damage. Tysabri is an immunomodulating medication, meaning it changes the way immune cells are released and how they move throughout the body. Similarly to immunosuppressants, the end result is the weakening of our over-active immune systems, and a decreased immune response. The goal is to keep immune cells from crossing the blood brain barrier and attacking our myelin, but it also keeps the immune system from fighting off foreign invaders which means there is a higher risk for infections.

    If you are on drugs that weaken your immune system taking anything “immune-boosting” is generally not recommended. After all it doesn’t make much sense to take one drug that weakens our immune response, and another drug (or supplement) that boosts it 🙂

    Great question!

  • Joma
    5 years ago

    That was an amazing description. Very funny. Unless you found a way to magically work in a Game of Thrones reference, it could not have been written any better!

    Seriously….well done!

  • Tracey
    5 years ago

    thank you so much for this description of the immune system. I get it now. I guess there is no reason not to get a flu shot now eh? Makes me wonder why my body is doing this to me though.

  • YHenn
    5 years ago

    This is a great, super helpful and easy to understand article! I can totally picture the ‘cops checking IDs. 🙂 Thanks!

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