1. Department of Paediatric Oncology/Haematology; Erasmus MC; Rotterdam; The Netherlands
2. Dutch Childhood Oncology Group; The Hague; The Netherlands
3. Department of Immunology; Erasmus MC; University Medical Centre Rotterdam; Rotterdam; The Netherlands
4. Royal Hospital for Sick Children; Glasgow; UK
5. Department of Haematology; Erasmus MC; University Medical Centre Rotterdam; Rotterdam; The Netherlands