[1] Kantonsspital, Dept Internal Med, Div Haematol, CH-6000 Luzern 16, Switzerland
[2] Free Univ Amsterdam, Acad Hosp, Dept Internal Med, Amsterdam, Netherlands
[3] Netherlands Red Cross, Blood Transfus Serv, Cent Lab, Amsterdam, Netherlands
[4] Aventis Behring AG, Zurich, Switzerland
[5] Univ Hosp Bern, Inselpital, Dept Intens Care, CH-3010 Bern, Switzerland
[6] Univ Hosp Bern, Inselpital, Cent Hematol Lab, CH-3010 Bern, Switzerland