Is Chronic Spontaneous Urticaria (CSU) an Autoimmune Disease?

Chronic spontaneous urticaria (CSU) is a condition that causes recurring episodes of red, bumpy, itchy skin called hives or hives. Most experts now believe that autoimmunity plays a role in most cases of chronic spontaneous urticaria (CSU), but the science continues to evolve.

An autoimmune disease is a chronic illness in which part of your immune system mistakenly attacks part of your own body. This leads to inflammation and damage.

Symptoms of chronic spontaneous urticaria occur when a type of immune cell called a mast cell is activated. The reason for this activation depends on the type of CSU you have.

There are two main types of CSU. They have the same symptoms but slightly different causes. Many scientists now think both these subtypes are autoimmune.

Type 1 CSU

Type 1 CSU, sometimes called autoimmune type 1 CSU, involves a part of the immune system called IgE antibodies. Some of these antibodies are abnormally programmed to attack some of your own proteins. If IgE encounters one of these proteins, it triggers mast cell activation.

People with type 1 CSU tend to have less severe symptoms than those with the other type of CSU. They are also less likely to suffer from other autoimmune diseases.

CSU type 2b

This type is sometimes called autoimmune CSU type 2b. With this type, another type of antibody, called IgM, is abnormally programmed. For example, IgM antibodies may begin to attack parts of IgE antibodies. This also triggers mast cell activation, triggering symptoms.

Other unknown types

About a third of people with CSU have no known subtype. It is not known whether they have another undiscovered type of autoimmune CSU or another problem causing their symptoms.

CSU and an allergic reaction share similar characteristics, including their causes. In both cases, the immune system is involved. Specifically, symptoms appear when mast cells are activated. The symptoms of a CSU episode and an allergic reaction are also similar.

A main difference between the two conditions is that, in CSU, symptoms occur spontaneously, without a known trigger. An allergic response is triggered when the immune system overreacts to harmless environmental triggers, such as pollen.

CSU does not directly cause other autoimmune diseases. However, people with CSU appear to have an increased risk of suffering from other autoimmune diseases, such as:

• Autoimmune hypothyroidism
• Autoimmune hyperthyroidism
• Celiac disease
• Lupus
• Rheumatoid arthritis

If you think you may have CSU, talk to a healthcare professional about your concerns. Take photos of your rash to show your provider, and tell them if the area was bumpy or flat. If you experience serious symptoms, such as difficulty breathing or a rash with fever, seek medical attention immediately.