Replacement therapy in adults, and children and adolescents (0-18 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, and children and adolescents (0-18 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) - Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) - Multifocal motor neuropathy (MMN)