Molecules, also known as Human Leukocyte Antigens (HLA), found on all nucleated cells in the body. Inherited from one' parents, histocompatibility antigens help the immune system to recognize whether or not a cell is foreign to the body. These antigens are used to help determine the compatibility of kidneys and pancreata for transplantation from one individual to another. See Human Leukocyte Antigen System (HLA System).