[1] Univ Med Ctr Utrecht, Paediat Blood & Marrow Transplantat Programme, NL-3508 AB Utrecht, Netherlands
[2] Univ Med Ctr Utrecht, Lab Translat Immunol, NL-3508 AB Utrecht, Netherlands
[3] Univ Minnesota, Dept Pediat, Program Blood & Marrow Transplantat, Minneapolis, MN 55455 USA
[4] Royal Manchester Childrens Hosp, Dept Haematol BMT, Manchester M27 1HA, Lancs, England