The immune system makes an abundance of proteins called antibodies. Antibodies are made by white blood cells (B cells). The antibodies recognize and combat infectious organisms (germs) in the body. Antibodies develop in our immune system to help the body fight infectious organisms. When an antibody recognizes the foreign proteins of an infectious organism, it recruits other proteins and cells to fight off the infection. This cascade of attack is called inflammation.
Sometimes these antibodies make a mistake, identifying normal, naturally-occurring proteins in our bodies as being “foreign” and dangerous. When these antibodies make incorrect calls, identifying a naturally-occurring protein (or self protein) as foreign, they are called autoantibodies. Autoantibodies start the cascade of inflammation, causing the body to attack itself. The antibodies that target “normal” proteins within the nucleus of a cell are called antinuclear antibodies (ANA). Most of us have autoantibodies, but typically in small amounts. The presence of large amount of autoantibodies or ANAs can indicate an autoimmune disease. ANAs could signal the body to begin attacking itself which can lead to autoimmune diseases, including lupus, scleroderma, Sjögren’s syndrome, polymyositis/dermatomyositis, mixed connective tissue disease, drug-induced lupus, and autoimmune hepatitis. A positive ANA can also be seen in juvenile arthritis.