1. From the Leukaemia Research Fund Immunodiagnostics Unit, University Department of Cellular Science, John Radcliffe Hospital, Oxford, UK; CIGH/CNRS 8291 and Laboratoire Central d'Anatomie Pathologie, CHU Toulouse Purpan, Toulouse, France; and the Department of Experimental Oncology, St Jude Children's Research Hospital, Memphis, TN.