UK United Kingdom

Explainer: what are autoimmune diseases?

Autoimmune diseases, which include a range of around 80 different illnesses from rheumatoid arthritis to type 1 diabetes and multiple sclerosis, occur when the immune system attacks the body. These diseases…

When cells attack - autoimmune disease develop when immune cells mistakenly attack a part of the body. Ari Moore/Flickr, CC BY-NC-SA

Autoimmune diseases, which include a range of around 80 different illnesses from rheumatoid arthritis to type 1 diabetes and multiple sclerosis, occur when the immune system attacks the body.

These diseases are fairly common, affecting around one in 20 people in Australia and New Zealand, but they’re often under-appreciated because although they lead to long-term debilitating disease, they’re rarely a primary cause of death.

The autoimmune response

The immune system protects the body by recognising and dealing with a wide range of infectious agents, including viruses, bacteria, fungi and parasites (collectively known as pathogens). It functions like an army, patrolling the body looking for pathogens, and either containing them or killing them before they can cause infection and illness.

In order to handle a broad range of pathogens, the immune system produces millions of individual cells with the capacity to detect different, randomly generated targets. Since the immune system has no way of knowing what pathogen it may encounter, this approach gives it the ability to detect a nearly limitless range of targets.

When an immune cell first encounters its target, it replicates, so a large number of cells are able to recognise that same target. This provides the immune system with enough cells to contain and kill that pathogen as well as a stockpile of cells that will recognise the target quickly in the future.

This is how vaccination works – the vaccine causes replication of immune cells that can target specific pathogens and protect from future infections.

One unfortunate side effect of producing cells that can recognise so many targets is that some cells will recognise targets within our own bodies. Under normal conditions, these cells are removed from the system, so they don’t attack.

But in some people – for reasons that remain poorly understood – these cells are not removed. The cells think they’re attacking a pathogen when they attack the body – and they cause autoimmune disease. Each autoimmune disease results from immune cells attacking a different target within the body.

Similar conditions, such as asthma and allergies, are often confused with autoimmune diseases. But they’re not considered to be autoimmune because they don’t result from immune cells attacking their own body. Rather, they’re caused by immune cells recognising and reacting to a target that doesn’t cause disease, such as pollen in allergic asthma or peanut protein in food allergies.

Treatments for autoimmune diseases

Current approaches to treating autoimmune disease control symptoms rather than cure. In most cases, treatments known as functional replacement therapies replace a function that’s lost during disease (such as insulin injections in type I diabetes).

These treatments are often combined with anti-inflammatory medications, which limit the amount of damage being caused by the immune response. Several more recent therapies also block specific components of the immune response.

Peanut allergy is not an autoimmune disease because it doesn’t result from immune cells attacking the body. GFAF Expo/Flickr, CC BY-NC-SA

In severe cases, medications that completely block immune responses are used to reduce disease symptoms. This is known as immunosuppression, and these medications require a delicate balancing act; while blocking the immune response may protect from autoimmune disease, this unfortunately leaves the individual open to severe infections.

Three common autoimmune diseases

There are many recognised autoimmune diseases and a growing list of illnesses not traditionally thought to be linked to the immune system, such as schizophrenia and narcolepsy, are now being recognised as having autoimmune components.

Here’s how three common autoimmune diseases work.

Approximately 10% to 15% diabetics have the autoimmune form of the disease, known as type 1 diabetes.

Formerly known as insulin-dependent or juvenile diabetes, this illness is caused when the immune system attacks the beta cells in the pancreas. The pancreas is a gland located behind the stomach and beta cells normally produce insulin (beta cells are still present in type 2 diabetes but no longer respond properly to the body’s demand for insulin).

Insulin regulates levels of sugar (glucose) in the body, ensuring you store and break it down properly. In the absence of insulin, the body starts to use fat as a substitute energy source, leading to a build-up of dangerous chemicals in the body which can cause a potentially fatal condition known as ketoacidosis.

Type 1 diabetes is generally treated using insulin injections and by monitoring blood sugar levels.

Multiple sclerosis affects the nervous system. Nerve cells in the brain and spinal cord communicate signals throughout the body and are wrapped in a protective cover called myelin that allows these signals to travel quickly.

The immune system attacks and damages this covering in people with multiple sclerosis, interfering with signals and causing a wide variety of physical and mental symptoms. The body is unable to repair the damage, and symptoms generally get progressively worse.

The patterns of autoimmune attacks can differ between people resulting in slightly different forms of disease. Some people get steadily worse while others have many short attacks, with stable periods in between. Current medications can only slow disease progression and manage symptoms.

Arthritis is a term for a range of conditions that result in damage to the joints, causing swelling, pain, stiffness and decreased movement. While different forms of arthritis have different causes, rheumatoid arthritis results from an autoimmune response against targets within the joint.

In rheumatoid arthritis, immune cells attack the joint surface damaging the cartilage that normally coats the bone, leading to bone grinding directly on bone. This leads to permanent damage to the bone and tissues surrounding the joint, causing pain and decreasing mobility.

The number of autoimmune diseases is growing as we discover more and more illnesses have an underlying autoimmune component. Current therapies mainly aim to replace a lost function in patients, or to broadly block inflammation.

Only through an improved understanding of how autoimmune disease starts and how each disease develops will we be able to provide improved therapies and ultimately cure these diseases.

Sign in to Favourite

Join the conversation

24 Comments sorted by

  1. Comment removed by moderator.

  2. Comment removed by moderator.

  3. Lynne Heal

    logged in via Twitter

    Multiple sclerosis is also known as a vascular disease also. CCSVI is the new way forward and being ignored because too many fear job losses as so much is being made via the MS drugs for profits, shares and commissions. NO MS drug has ever cured MS and never will. If someone scrutinizes MS truths they will wake up to billions being made by so many people via MS drugs. Some of these drugs have caused deaths also and no one has delved into how many have died with MS on MS drugs. MS societys have also made billions too. A lawsuit is ahead towards a neurologist whos naysayed CCSVI. Theres lots of frauds and corruptions going on. Pharmacueticals are also part of too

    1. Paul Rogers


      In reply to Lynne Heal

      Lynne, CCSVI (constricted neck veins) is not widely accepted as a cause of MS, and a recent study seems to disprove the theory.

  4. john byatt

    retired and cranky at RAN Veteran

    Have had rheumatoid arthritis for thirty five years, first diagnosed as polyviral arthritis, It burnt itself out pretty much five years ago, only getting small flare ups now, for the first twenty five years it was very painful and the wife would notice from my face when an attack was in progress, I have been left with very little physical abnormalities and a few years ago asked my doctor why, was i just lucky?

    he replied no, you did what you were told.

  5. Andrew Kewley
    Andrew Kewley is a Friend of The Conversation.


    I don't want to be too critical, but this article is overly simplistic in my opinion and doesn't really discuss any of the particularly novel aspects of the adaptive immune system. For example, the Germinal centre where B lymphocytes replicate and are selected to evolve (in a microevolutionary sense) antibodies that bind to targets with greater affinity. It is amazing that the immune system can start with what is essentially a fairly random/generic antibody to a particular target (such as a new infection…

    Read more
    1. john byatt

      retired and cranky at RAN Veteran

      In reply to Andrew Kewley

      If you want to experience the pain of rheumatoid in your shoulders then it is quite easy, just lay a bag of cement across and spend the whole day like that, courses of prednisone not only gave relief from the pain but more importantly stopped the destruction of the joints, of course there were side affects, i had cataracts, fixed by surgery, comparing the side effects to a life with a crippled up painful body, give me the prednisone any day. The methotrexate however did give me a bit of a chuckle…

      Read more
  6. Comment removed by moderator.

  7. Peter Davies

    Bio-refinery technology developer

    A very simplistic article. My wife has the dubious privilege of being formally diagnosed with 4 auto immune disorders: Lupus SLE, Fibromyalgia, Sarcoidosis and Sjogren's Syndrome. A US lab specialising in this area are finding that "different" diseases are really alternate manifestations of the same problem, and offered free assistance to my wife, so long as we could get a Australian University to also participate in documenting and participate in research transfer/collaboration. Not one is interested, not enough grant money in it apparently.

    1. Edwina Laginestra
      Edwina Laginestra is a Friend of The Conversation.

      Jack of all trades

      In reply to Peter Davies

      It is an "Explainer" - it is meant to be simplistic. Many people do not understand what an autoimmune disease is, why I can't treat it, why I'm not sick all the time, and even what I have - as symptoms can vary. I found this a good starting point.

      I'd agree that the different diseases your wife has been diagnosed with are probably her manifestation of auto-immune response - I've found that the doctors like a label, and these are the ones that have labels. There are lots of other symptoms that will take you out of those boxes and then they are not sure. So you get "probably XXX", despite missing the most common symptom.

      The more you look into it, the more you realise that other symptoms you've had (or will get) could easily be related back to a "not-normal" body response. Some of us just seem to work this way.

    2. Peter Davies

      Bio-refinery technology developer

      In reply to Edwina Laginestra

      Edwina, I would normally agree about the "explainer" bit, but in this case a simple list of autoimmune diseases if included would have been far better than just selecting a couple such as Type 1 Diabetes, Multiple sclerosis or Rheumatoid arthritis.

      Yes labeling is common practice and openly admitted by our GP's as a problem for patients such as my wife who are "outside the box". Yes agree also on symptom spotting, particularly for other family members, who occasionally raise this with their GP, have the specific tests and turn up positive, otherwise going undiagnosed. Not that this makes a great difference in terms of treatment options available here in the lucky country, but it does limit the psychiatric referrals....

    3. Elena Berwick


      In reply to Peter Davies

      Peter, I trust that herbal medicines can effectively resolve autoimmune issues depending on their stages. For example, I am personally aware of the fact when sarcoidosis was treated in several months (six or seven, something like that) with herbal medicines from India. Please don't underestimate the power of herbs.

      On the other hand, chemicals like antinflamatory medicines can cause immediate issues with a gastrointestinal system. So, the next problems might be ulcers and then issues just go on and on.

    4. Peter Davies

      Bio-refinery technology developer

      In reply to Elena Berwick

      When there is no effective treatment offered by our medical profession, but the treatments they try cause far more harm, you do tend to start looking at alternatives, so far these have only provided a little temporary relief. The US researchers we spoke to believed that the problems are triggered by environmental factors, effectively a form of allergy.

  8. Tom Hennessy


    Porphyria is considered to be an autoimmune disease. Porphyria is shown to be induced by iron. So, one might conclude, iron causes autoimmune disease?
    "Deficiency in detoxification and increased oxidative stress can result in the development of a systemic autoimmune disease"

    1. john byatt

      retired and cranky at RAN Veteran

      In reply to Tom Hennessy

      The word i think is trigger, not cause

      many viral infections can trigger rheumatoid

    2. Tom Hennessy


      In reply to john byatt

      They've already shown, in Juvenile Rheumatoid Arthritis, the iron they give then to treat their 'anemia', goes right to their joints, and they said they should do a study to see if iron from their food was harming them too, but never did the study.
      "We found that iron excessively accumulates in arthritic joints and probably contributes to the chronic damage,"
      Same with you one might suppose, the iron from your food may be hurting you?
      "Antianemic and potential anti-inflammatory activity of
      desferrioxamine: possible usefulness in rheumatoid arthritis."
      "higher deposition of iron in rheumatoid muscle as compared with normals."

    3. john byatt

      retired and cranky at RAN Veteran

      In reply to Tom Hennessy

      " iron excessively accumulates in arthritic joints'

      iron is essential

      oxygen is also killing you,

      leave it to the experts Tom

    4. john byatt

      retired and cranky at RAN Veteran

      In reply to Tom Hennessy

      then try to work out what is being said

      " in genetic hemochromatosis"


    5. Tom Hennessy


      In reply to john byatt

      It is a 'human model of iron excess', and phlebotmy decreases oxidation, proving therefore increased iron causes increased oxidation and said removal of the iron by phlebotomy decreases the oxidation. So, if there is 'extra iron' in rheumatoid arthritis, just as there is in juvenile rheumatoid arthritis, one might assume the removal of said iron by phlebotomy may decrease oxidation, at the very least, leaving one with the wonder, does the lowering of iron by phlebotomy leave one with the same moderate revcovery in general rheumatoid arthritis, as does the iron chelator desferoxamine leads to moderate recovery?
      "Therapy by taking away: the case of iron."
      "Iron Metabolism in Children with Juvenile Rheumatoid Arthritis"

    6. Tom Hennessy


      In reply to john byatt

      Anemia? Obviously not iron deficient anemia, because giving the person with rheumatoid arthritis the iron chelator desferrioxamine, their anemia and pain is relieved.
      "Antianemic and potential anti-inflammatory activity of
      desferrioxamine" "moderate improvement of the pain intensity, morning stiffness and Ritchie's index was also observed"

    7. Tom Hennessy


      In reply to john byatt

      "Those who were anaemic (haemoglobin <115 g/l in women and <130 g/l in men, which are the lower limits of normal range of haemoglobin concentration for the local laboratory1) "

      The marker to define anemia is too high. Women don't get preeclampsia or gestational diabetes if their hemoglobin is 11, considered anemic, and people on dialysis begin to die when their hemoglobin is raised to 13.5 so, evidence based, one might wonder whether the marker, hemoglobin, defines healthy levels of red blood cells or not, just as other researchers have questioned the appropriate cutoff of hemoglobin in children.
      "The diagnostic criteria for iron deficiency in infants should be reevaluated"

      The anemia found in rheumatoid arthritis is due to anemia of chronic disease, the body withholding iron from the invader.
      "Role of Interleukin-6 in the Anemia of Chronic Disease"