[1] NETHERLANDS RED CROSS,BLOOD TRANSFUS SERV,CENT LAB,DEPT CLIN VIROIMMUNOL,NL-1066 CX AMSTERDAM,NETHERLANDS
[2] UNIV AMSTERDAM,EXPT & CLIN IMMUNOL LAB,AMSTERDAM,NETHERLANDS
[3] UNIV AMSTERDAM,ACAD MED CTR,DEPT INTERNAL MED,NL-1105 AZ AMSTERDAM,NETHERLANDS
[4] MUNICIPAL HLTH SERV,AMSTERDAM,NETHERLANDS