According to the leading experts in immunology, when part of the immune system is either absent or not functioning properly, it can result in an immune deficiency disease. When the cause of this deficiency is hereditary or genetic, it is called a immune deficiency.
The immune system is composed of white blood cells. These cells are made in the bone marrow and travel through the bloodstream and lymph nodes. They protect and defend against attacks by “foreign” invaders such as germs, bacteria and fungi. Antibodies are proteins that are made in response to infection or immunization and help fight infections. Complement is another blood protein that plays a protective role in the immune system.