Fig. 1.

Schematic description of multiplex homogenous proximity ligation assay. (1) The samples are incubated with 23 pairs of proximity probes in 1 μl sample. (2) Upon proximal binding of the pairs of PLA probes to a common antigen the oligonucleotide sequences are ligated using a connector oligonucleotide. (3) The ligated products are amplified in multiplex using all pre-amplification primers simultaneously. (4) This is followed by quantification of each biomarker by quantitative real time PCR using only the unique primer pair for a given analyte.