Parallel reaction monitoring assay development for multiple sclerosis biomarkers in cerebrospinal fluid.

We have developed and tested parallel reaction monitoring (PRM) assays for 25 proteins highly relevant as cerebrospinal fluid (CSF) biomarkers for multiple sclerosis, representing various biological processes affected in the disease. The proteins were represented by 72 peptides selected according to relevant guidelines and available literature. Stability testing revealed 64 peptides with low intra- and inter-day variations, with 44 also being stably digested after 16 hours of trypsin digestion, and 37 furthermore showing a significant difference between multiple sclerosis and controls, thereby confirming literature findings. Calibration curves were developed using spike-in of synthetic light and heavy peptides in rat plasma.