Replacement therapy in adults, and children and adolescents in:- Primary immunodeficiency syndromes with impaired antibody production - Hypogammaglobulinaemia and recurrent bacterial infections in patients with chronic lymphocytic leukaemia, in whom prophylactic antibiotics have failed- Hypogammaglobulinaemia and recurrent bacterial infections in plateau phase multiple myeloma patients who have failed to respond to pneumococcal immunisation- Congenital AIDS with recurrent bacterial infectionsImmunomodulation in adults, and children and adolescents in:- Primary immune thrombocytopenia (ITP), in patients at high risk of bleeding or prior to surgery to correct the platelet count- Guillain Barré syndrome- Kawasaki disease