Autoimmune ArthritisAutoimmune Arthritis diseases are systemic illness that affect the entire body. You can't have it just in your knee.What Is Autoimmune Arthritis? - wiseGEEK: clear answers for common ...Autoimmune arthritis is a type of arthritis caused by abnormalities in the immune system that make the body attack its own joints...Rheumatoid Arthritis (RA) and Autoimmune DiseasesWebMD explains what makes RA an autoimmune disease. Learn what autoimmune diseases are and how changes involving your immune system lead to RA.