Replacement therapy in adults, children and adolescents (0 to 18 years) in: - Primary immunodeficiency syndromes (PID) with impaired antibody production. - Secondary immunodeficiencies (SID) in patients who suffer from severe or recurrent infections, ineffective antimicrobial treatment and either proven specific antibody failure (PSAF)* or serum IgG level of < 4 g/L.*PSAF = failure to mount at least a 2-fold rise in IgG antibody titre to pneumococcal polysaccharide and polypeptide antigen vaccinesImmunomodulation in adults, children and adolescents (0 to 18 years) 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 (in conjunction with acetylsalicylic acid; see section 4.2). - Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). - Multifocal Motor Neuropathy (MMN).