[1] Royal Marsden Hosp, Acad Dept Haematol & Cytogenet, London SW3 6JJ, England
[2] Fac Med, GEIL, Immunol Lab, Nancy, France
[3] Serv Hematol, Dijon, France
[4] Inst Jules Bordet, B-1000 Brussels, Belgium
[5] Humboldt Univ, Robert Rossle Clin Charite, Berlin, Germany
[6] Univ Ferrara, Inst Haematol, I-44100 Ferrara, Italy