ANA (antinuclear antibodies): ANA testing is a screening tool used to detect the presence of antibodies that target the cell nucleus. It is a broad test that can indicate the possibility of an autoimmune condition, as many autoimmune diseases are associated with the production of ANA. Rheumatoid factor: Rheumatoid factor is an antibody directed against the Fc portion of immunoglobulin G (IgG). It is primarily used in the diagnosis of rheumatoid arthritis (RA). Elevated levels of rheumatoid facto

Autoantibody diseases impact more than 240 million people worldwide. See how J&J researchers are working to help patients that have abnormal immune responses to viruses. | Johnson & Johnson

What if your immune system started attacking you, instead of protecting you? The Associated Press is looking at autoimmune diseases, the immune system's dark side. | AP