Definition: The spleen is an abdominal organ that is part of the immune system. It's located on the left side of the body beside the stomach, but under the diaphragm. The spleen has several important functions (as do most of the body's organs!) -- it assists with immune system maintenance, including producing a type of white blood cell (certain lymphocytes), getting rid of worn out or damaged red blood cells and storing blood. Under abnormal circumstances it may become an alternative site for the creation of blood cell precursors (which normally takes place in the bone marrow).
A problem with the spleen is usually a sign of a bigger problem. There many diseases that can cause problems in the spleen. The spleen can be a concern to people with hepatitis because it's often affected in chronic liver disease. For example, an enlarged spleen (splenomegaly) is one of the complications of cirrhosis. The spleen also plays a small role in jaundice, one of the symptoms of acute viral hepatitis.
