1. Department of Parasitology, Biomolecular Mass Spectrometry Unit, Leiden University Medical Center, Leiden, The Netherlands, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany, Central Division of Analytical Chemistry, Forschungszentrum Jülich, Jülich, Germany, and Department of Rheumatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands