The human immune system is a delicately controlled system of complex operations in which the body’s cells work together to detect and destroy harmful, foreign substances called antigens. Common antigens include bacteria, viruses, and toxins.
When an individual develops an autoimmune disorder, the immune system can no longer differentiate between foreign invaders and the body’s own tissues. As a result, the immune cells are sent errant messages to begin destroying healthy body tissue.
Two common types of autoimmune disease include rheumatoid arthritis and reactive arthritis, in which the joints and surrounding tissues become the target of attack.