1. Department of Haematology, Leiden University Hospital, Leiden,
2. Dutch Childhood Leukaemia Study Group, The Hague,
3. Department of Haematology
4. Central Laboratory, Red Cross Blood Transfusion Service, Amsterdam,
5. St Franciscus Hospital, Roosendaal, The Netherlands
6. Clinical and Tumour Immunology, Daniel den Hoed Cancer Centre, Rotterdam,