Blood protein for transfusions. Human immunoglobulin stored as dried crystals in a bottle (left bottle). This can be dissolved in purified water (right bottle) to create a solution for intravenous transfusion into the bloodstream. Immunoglobulins (antibodies) are proteins made by the white blood cells of the body's immune system to fight off infections. Administering immunoglobulin solution is used to treat patients with defective immune systems, such as those with AIDS (Acquired Immune Deficiency Syndrome), leukaemia or rheumatoid arthritis. This storage form of immunoglobulin is made by isolating it from the plasma (liquid component) of healthy blood.