What is the spleen?
• The spleen is a part of the immune system and is located in the upper left side of the abdomen.
• While the spleen is useful, it's not essential. The organ's primary functions are filtering the blood by disposing of old or damaged blood cells and platelets and helping the immune system by killing bacteria and other foreign substances.
• The operation to remove the organ is called a splenectomy.
• If the spleen is removed, certain immunizations are needed to help prevent infections that the spleen normally fights.
-- Source: WebMD.com