Fig. 1

Schematic overview of the competitive ELISA technique. Before transfer onto plates coated with α-synuclein monomer, plasma samples are incubated for 1 h at RT with α-synuclein monomer. Following washing steps, the competition reaction is created by moving plasma/α-synuclein monomer samples onto the coated plate. Here, high affinity antibodies form more stable bonds with free antigen than do lower affinity antibodies. Consequently, lower affinity antibodies remain bound to the excess immobilized antigen on the plates, but high-affinity antibodies bound to the fluid-phase antigen are washed away. After several washes, the amounts of low-affinity antibodies remaining on the plates are detected by peroxidase-labelled polyclonal goat anti-human IgG (Fc fragment specific). The plate is developed by adding an enzymatic substrate to produce a visible signal