Liquid-phase anion-exchange fractionation of plasma samples was carried out using the ProteinChipH Fractionation Kit (Bio-Rad) according to the manufacturer's instructions with a Biomek 3000 Laboratory Automation Workstation. Six fractions were obtained from each sample eluting at pH 9.0 (f1), pH 7.0 (f2), pH 5.0 (f3), pH 4.0 (f4), pH 3.0 (f5) and organic phase (f6).