[1] Vrije Univ Amsterdam, Dept Chem & Pharmaceut Sci, Div BioAnalyt Chem, NL-1081 HV Amsterdam, Netherlands
[2] Ludger Ltd, Culham Sci Ctr, Abingdon, Oxon, England
[3] Leiden Univ, Med Ctr, Ctr Prote & Metabol, Leiden, Netherlands
[4] Leiden Univ, Med Ctr, Dept Rheumatol, Leiden, Netherlands
[5] CNRS, UMR 8576, Villeneuve Dascq, France
[6] Roche Diagnost GmbH, Pharma Biotech Dev Penzberg, Penzberg, Germany