Human immunoglobulin as dried crystals in bottles. This can be dissolved in solution for clinical use by intravenous transfusion into the bloodstream. It is an antibody made by the white blood cells of the body's immune system to fight off infections. It is used to treat immunodeficiency diseases like AIDS (Acquired Immume Deficiency Syndrome). It is also used to treat other disease such as leukaemia and rheumatoid arthritis. The immunoglobulin is a blood protein, and it is prepared from donor blood where it is found dissolved in the liquid plasma part of the blood.