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What is autoimmunity?

One of the functions of the immune system is to protect the body by responding to invading microorganisms, such as viruses or bacteria, by producing antibodies or sensitized lymphocytes (types of white blood cells). Under normal conditions, an immune response cannot be triggered against the cells of one’s own body. In certain cases, however, immune cells make a mistake and attack the very cells that they are meant to protect. This can lead to a variety of autoimmune diseases. They encompass a broad category of related diseases in which the person’s immune system attacks his or her own tissue.

What causes autoimmunity?

The immune system normally can distinguish “self” from “non-self.” Some lymphocytes are capable of reacting against self, resulting in an autoimmune reaction. Ordinarily these lymphocytes are suppressed. Autoimmunity occurs naturally in everyone to some degree; and in most people, it does not result in diseases. Autoimmune diseases occur when there is some interruption of the usual control process, allowing lymphocytes to avoid suppression, or when there is an alteration in some body tissue so that it is no longer recognized as “self” and is thus attacked. The exact mechanisms causing these changes are not completely understood; but bacteria, viruses, toxins, and some drugs may play a role in triggering an autoimmune process in someone who already has a genetic (inherited) predisposition to develop such a disorder. It is theorized that the inflammation initiated by these agents, toxic or infectious, somehow provokes in the body a “sensitization” (autoimmune reaction) in the involved tissues.

What are the types of autoimmunity?

Autoimmune disorders are frequently classified into organ-specific disorders and non-organ-specific types. Autoimmune processes can have various results, for example, slow destruction of a specific type of cells or tissue, stimulation of an organ into excessive growth, or interference in its function. Organs and tissues frequently affected include the endocrine gland, such as thyroid, pancreas, and adrenal glands; components of the blood, such as red blood cells; and the connective tissues, skin, muscles, and joints. Some autoimmune diseases fall between the two types. Patients may experience several organ-specific diseases at the same time. There is little overlap between the two ends of the spectrum.

In organ-specific disorders, the autoimmune process is directed mostly against one organ. Examples, with the organ affected, include Hashimoto’s thyroiditis (thyroid gland), pernicious anemia (stomach), Addison’s disease (adrenal glands), and type 1 diabetes (pancreas).

In non-organ-specific disorders, autoimmune activity is widely spread throughout the body. Examples include rheumatoid arthritis, systemic lupus erythematosus (SLE or lupus), and dermatomyositis.

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Who does autoimmunity impact?

While autoimmune diseases can affect anyone, different groups are more susceptible to certain autoimmune diseases. In lupus, for example, African-American women are three times more likely to get lupus than white women.6  Lupus is also more common in Hispanic, Asian, and Native American and Alaskan Native women.7

Impact on women

Research shows autoimmune diseases are more common in women, occurring at a rate of 2 to 1. Many autoimmune disorders tend to affect women during periods of extensive stress, such as pregnancy, or during a great hormonal change. More women are affected every year with autoimmune diseases, leading to increased research to identify the causes.

Impact on families

Autoimmune diseases tend to occur in families. If there’s one case of autoimmune disease in the family, there’s likely to be another. However, it is not a particular autoimmune disease that runs in families, but it is a tendency to autoimmunity. One family member may have lupus, another family member may have Sjögren’s disease, a third member may have rheumatoid arthritis.

Autoimmune diseases by the numbers

Scientists are continuing to learn more about autoimmune diseases on a daily basis.

100 +

Autoimmune diseases are a group of more than 100 chronic conditions.

50 MM

In the U.S., autoimmune diseases affect more than 50 million people, while 8 million more have auto-antibodies.

25 %

Autoimmune diseases cluster - among Americans who have autoimmune disease, up to 25% have more than one.

80 %

Approximately 80% of all patients diagnosed with autoimmune diseases are women.

Get a diagnosis of an autoimmune disease

For people living with autoimmune diseases, getting a diagnosis can prove challenging. We’ve compiled tips to ease this process.