Your immune system fights off infection and disease. It has a number of ways to detect and destroy anything it recognizes as foreign to your body, including bacteria, viruses, fungi, parasites or unhealthy cells such as cancer cells. In some people, the immune system goes into overdrive, causing the body to see its own cells as foreign and attack them. This leads to what we call autoimmune diseases, such as Crohn’s disease, rheumatoid arthritis and lupus.
