Your immune system works hard to protect your body from invading viruses and bacteria, but things don’t always go as planned. If you have an autoimmune disease like myasthenia gravis (MG), the immune system mistakenly attacks your own body. If it’s not controlled with medications, myasthenia gravis can lead to muscle weakness, including double vision and sagging eyelids.

In this article, we’ll discuss how myasthenia gravis affects your immune system and why it’s considered an autoimmune disease. We’ll also cover different treatments used to dampen the immune system to manage MG symptoms.

What Is an Autoimmune Disease?

Autoimmune diseases occur when the body’s immune system mistakes healthy cells or tissues for harmful invaders. Immune cells can recognize specific proteins or patterns — known as antigens — on the surface of bacteria, viruses, and even cancer cells. When the immune system recognizes an antigen, it activates an “alarm” that tells immune cells to attack.

Antibodies, also called immunoglobulins, are specialized immune system proteins that recognize and bind to antigens. They act like red flags that tag invaders and kick off an immune response. Immune cells look for these tags so that they know which invaders to target and destroy.

Normally, your immune system makes antibodies only when you’re exposed to a new antigen — for instance, a new strain of the seasonal flu virus. However, people with autoimmune diseases have abnormal antibodies that target antigens on their own cells. These are known as autoantibodies. When healthy cells get tagged by autoantibodies, the immune system attacks them as if they were something strange and dangerous.

Myasthenia Gravis Is an Autoimmune Disease

In myasthenia gravis, the immune system mistakenly attacks the neuromuscular junction (NMJ). This is the space in the nervous system where the nerves and muscles communicate with one another. The nerves send the neurotransmitter (chemical messenger) acetylcholine to the skeletal muscle fibers. When acetylcholine reaches the muscle, it binds to the acetylcholine receptors. This action tells your muscles to contract or tighten.

Specifically, people with myasthenia gravis have autoantibodies that attack the acetylcholine receptors (AChRs) on muscle cells. Without enough receptors, chemical messages can’t travel from the nerves to the muscles. This means the muscles can’t contract, which leads to muscle weakness and symptoms of myasthenia gravis.

Autoantibodies in Myasthenia Gravis

Everyone with myasthenia gravis has at least one autoantibody targeting the neuromuscular junction. Around 85 percent have AChR antibodies. People with AChR antibodies are more likely to experience certain symptoms, like generalized muscle weakness. They may also have ocular symptoms like ptosis (drooping eyelids) or double vision.

Some people have antibodies that target muscle-specific kinase (MuSK). Anti-MuSK antibodies interfere with communication between the nerves and muscles in the NMJ. Studies show that 40 percent of people who don’t have AChR antibodies have MuSK antibodies.

If you test negative for AChR and MuSK antibodies, you have seronegative myasthenia gravis. Your doctor can run another test for low-density lipoprotein receptor-related protein 4 (LRP4) antibodies. LRP4 is another protein found in the NMJ that works together with MuSK. Some research suggests that 2 percent of people with myasthenia gravis have LRP4 autoantibodies.

Treatment Involves Modifying the Immune System

Because myasthenia gravis is caused by an overactive immune system that mistakenly attacks the NMJ, doctors can prescribe medications to calm inflammation and slow disease progression. Some treatments also stop the immune system from making more autoantibodies.

It’s important to find a myasthenia gravis treatment plan that works best for you. If untreated, your symptoms can get worse over time. They may spread to other parts of the body, making it hard to go about your daily activities.

Corticosteroids

Corticosteroids (steroids) are usually one of the first treatment options to control MG symptoms. They work by suppressing the immune system and blocking autoantibody production. You may start by taking prednisone. However, long-term steroid use can come with serious side effects.

Immunosuppressants

To avoid these side effects, your doctor may prescribe an immunosuppressant. These medications dampen the immune system to treat myasthenia gravis. Examples include azathioprine and mycophenolate mofetil.

Neonatal Fc Receptor Blockers

Researchers have also developed new medications to reduce autoantibodies in the bloodstream. Neonatal Fc receptor (FcRn) blockers help your body clear out extra antibodies. The U.S. Food and Drug Administration (FDA) has approved two FcRn blockers for myasthenia gravis:

• Rozanolixizumab-noli (Rystiggo)
• Efgartigimod alfa-fcab (Vyvgart)

Studies show that these medications reduce antibodies and improve MG symptoms.

Rituximab

Rituximab is a biologic drug used to treat cancer and autoimmune disorders. It works by blocking specialized immune cells known as B cells. Your B cells are responsible for making antibodies. By blocking them, rituximab limits autoantibody production.

It’s important to note that the FDA hasn’t approved rituximab for treating myasthenia gravis. Your doctor may prescribe it “off-label,” or outside of its intended use.

Complement Inhibitors

The complement system is a complex part of the immune system. It works together with antibodies to destroy invading pathogens. Researchers have found that blocking complement proteins can stop autoimmune attacks and improve symptoms of myasthenia gravis. Examples include:

• Zilucoplan (Zilbrysq)
• Eculizumab (Soliris)
• Ravulizumab-cwvz (Ultomiris)

Thymectomy

Around 10 percent of people with myasthenia gravis have a thymoma or tumor on their thymus gland. This gland is partly responsible for making harmful autoantibodies. Your doctor may recommend a surgery called thymectomy to remove the thymus. Studies show that myasthenia gravis symptoms improve within a few years of the surgery.

Talk to Your Doctor About Myasthenia Gravis Treatment

If you’ve noticed any new or worsening myasthenia gravis symptoms, talk to your health care provider. They can change your treatment plan to better target your immune system. Doctors and researchers have found many new medications to better treat myasthenia gravis.

Remember, your treatment plan can always change. For example, many people with myasthenia gravis start out taking acetylcholinesterase inhibitors to block the breakdown of acetylcholine in the NMJ. If their symptoms don’t improve, doctors usually prescribe corticosteroids. Your health care provider will ensure that you continue to receive the best treatment for your myasthenia gravis.

Find Your Team

On MGteam, the social network for people living with myasthenia gravis and their loved ones, more than 1,000 members come together to ask questions, give advice, and share their stories with others who understand life with myasthenia gravis.

Are you currently taking a medication that modifies or suppresses your immune system to combat myasthenia gravis? Share your experience in the comments below, or start a conversation by posting on your Activities page.