Autoimmunity
Autoimmunity is a medical condition where a person’s immune system attacks that person’s own body.  A healthy immune system recognizes viruses, bacteria, and other pathogens, then fights them off.  When a person has autoimmunity, their immune system attacks the person’s own body.  It recognizes the body’s healthy cells and tissues as antigens, and reacts by attacking them.  Sometimes this reaction causes severe inflammation, which can be painful and even dangerous.  Sometimes the reaction is not dangerous and causes very few symptoms. Diseases caused by autoimmunity are called autoimmune diseases.