An autoimmune disorder occurs when the body’s immune system attacks and destroys healthy body tissue by mistake. There are more than 80 types of autoimmune disorders.
The white blood cells in the body’s immune system help protect against harmful substances. Examples include bacteria, viruses, toxins, cancer cells, and blood and tissue from outside the body. These substances contain antigens. The immune system produces antibodies against these antigens that enable it to destroy these harmful substances.
When you have an autoimmune disorder, your immune system does not distinguish between healthy tissue and antigens. As a result, the body sets off a reaction that destroys normal tissues.