α-Synuclein implicated in Parkinson’s disease is present in extracellular biological fluids, including human plasma

SPECIFIC AIMSWe investigated whether neuronal cells in culture normally secrete α-synuclein protein (α-syn) into their surrounding media. We also looked for the presence of α-syn in human cerebrospinal fluid (CSF) and blood plasma. The methods used were immunocapture with anti-α-syn antibodies coupled to magnetic beads, followed by detection on Western blots using five different antibodies to α-syn.PRINCIPAL FINDING1. Neuronal cells normally secrete α-synTo determine whether cells secrete α-syn during normal metabolism, we used human neuroblastoma M17 cells stably transfected with cDNA encoding the wild-type form of α-syn (M17-wt), untransfected M17 cells, or cells transfected with vector alone (M17-vec). Serum-free OPTI-MEM medium conditioned for 6–48 h with each cell type was immunoprecipitated using magnetic dynabeads coupled to 211 mouse monoclonal antibody which recognizes amino acid residues 121-125 of α-syn. Bound proteins were eluted from the beads, after washing, and separated on SDS-gels before ...