1. An antibody that an organism produces against any of its own tissues, cells, or cell components.
2. An antibody that reacts against normal substances present in the organism producing it and is present in autoimmune diseases.
3. An antibody directed against a self antigen, i.e., against a normal tissue constituent.

An antibody (immunoglobulin) formed in response to, and reacting against, one of the individual's own normal antigenic endogenous body constituents.

Predictive Antibodies"

• In autoimmune diseases, such as type 1 diabetes, the immune system mistakenly manufactures aintibodies that target the body's tissues.
• Certain of these "autoantibodies" appear many years before overt symptoms of any disease, suggesting that screening for these molecules could be used to predict who is at risk of falling ill.
• Autoantibodies might also serve as guides to disease severity and progression and might even warn of risk for some nonimmune disorders.
• Screening for predictive autoantibodies could one day become routine, although a scarcity of preventive treatments currently stands in the way.