Multiple sclerosis (MS) is an immune disorder. It’s also referred to as an immune-mediated disorder, an autoimmune disorder, and a neurological disorder.

Because the immune system is attacking a healthy part of the body, MS is an immune-mediated disorder (“mediated” means to transmit or effect). And because the immune attack happens within the central nervous system, it leads to neurological symptoms.

MS has long been called an autoimmune disorder, but some researchers in 2012 questioned whether that’s accurate.

In this article, we’ll discuss the immune system’s role in MS, early symptoms, and how blood tests are used to help diagnose MS.

A healthy immune system keeps you free from infection and disease. When it perceives a threat (antigen), it makes antibodies to mount an attack. An immune disorder is when the immune system overreacts and attacks healthy cells, tissues, or organs.

Diseases that happen due to an abnormal immune system response are called immune-mediated diseases.

Autoimmune diseases are a subset of immune-mediated diseases. The immune system misidentifies specific naturally occurring substances (autoantigens) as a threat and makes antibodies to fight them.

In a 2012 review article, researchers stated that MS leads to various neurological and autoimmune manifestations. They noted strong evidence that MS is at least partly an immune-mediated disease. They also said there’s less evidence that it’s a classical autoimmune disease.

The National MS Society (NMSS) calls MS an immune-mediated disease. This organization notes that most MS experts believe it to be an autoimmune disease, though no specific antigens have been identified in MS.

So, while there may be some question about it being an autoimmune disease, MS does involve an immune system misfire.

In MS, the immune system attacks myelin, a fatty substance that protects nerve fibers. It can also attack myelin-producing cells and nerve fibers beneath the myelin. Loss of myelin is called demyelination.

When the protective myelin coating is damaged, there’s a disruption in electrical signals in the central nervous system. This affects communication between the brain and the rest of the body.

Recurring attacks can leave you with multiple areas of scar tissue, or sclerosis. These areas of scarring are called lesions or plaques. They can occur in the:

  • brain stem or cerebellum
  • white matter around the brain ventricles
  • spinal cord
  • optic nerves

Symptoms of MS vary depending on the location and extent of the attack.

Because MS can affect different parts of the brain and spinal cord, symptoms can vary a lot from person to person. Symptoms also tend to change from month to month and throughout your life.

In relapsing forms of MS, attacks are followed by periods of remission, during which symptoms go away or become much less severe. Remissions can last a few weeks or for many years. Progressive forms of MS involve a steady decline in function over time.

While the list of potential symptoms is quite long, early symptoms often include:

  • blurry or double vision
  • optic neuritis
  • muscle weakness and stiffness
  • muscle spasms
  • numbness and tingling
  • dizziness, balance and coordination problems
  • bladder control problems

There’s no blood test that can diagnose MS. However, blood testing can help rule out some other conditions. They can also help guide the next steps toward diagnosis. Some of these conditions to rule out are:

  • Vitamin and mineral deficiencies.
  • Lupus. A positive antinuclear antibody test (ANA test) points more toward lupus than MS.
  • Neuromyelitis optica (NMO). A blood test called AQP4-IgG can detect antibodies for a specific astrocyte protein associated with NMO. Another antibody, MOG-IgG, is present in about half of those who do not have AQP4-IgG, but it’s rare in people with MS.
  • Sjögren’s. Blood tests can detect anti-Ro (SS-A) and anti-La (SS-B) antibodies, rheumatoid factor, and antinuclear antibodies. These are associated with Sjögren’s but not MS.
  • Lyme disease. Blood testing can determine if you have antibodies due to exposure to the Borrelia bacteria that causes Lyme disease.
  • Myasthenia gravis. Most people with myasthenia gravis have high levels of acetylcholine receptor antibodies. About half of those who don’t have these antibodies test positive for the anti-MuSK antibody.

Quite a few other conditions present in the same way as MS. There’s no specific test for MS, so it’s a challenging diagnosis. Symptoms and clinical history are important factors. In addition to blood tests to rule out other conditions, diagnostic testing may include:

  • MRI. MRI scans of the brain and spinal cord can help identify MS lesions. Contrast dye can sometimes show evidence of active lesions.
  • Lumbar puncture (spinal tap). A lumbar puncture is used to get a sample of cerebrospinal fluid. The fluid is tested for proteins and inflammatory cells associated with MS. Not everyone with MS has positive results.
  • Evoked potential tests. These tests measure how well the central nervous system and eyes respond to stimulation.

Results of these tests can help decide if you meet the diagnostic criteria for MS.

MS is an immune-mediated disorder. It’s often called an autoimmune disorder, but there’s some debate over whether it can be classified as such. Because MS attacks the central nervous system, it’s also a neurological disorder.

There’s no “MS test,” so it takes time and careful analysis to confirm a diagnosis.

Blood tests are quite useful in ruling out other causes for MS-like symptoms. Diagnosing MS also involves clinical history and neurological examination. Other tests, like MRI, lumbar puncture, and evoked potentials, help paint a complete picture.

If you have symptoms of MS, this process can feel rather frustrating. However, getting the right diagnosis is crucial to getting you the correct treatment.