he measurement of neuropeptides in human saliva could be a valuable tool to study patients with chronic painful disorders. All the studies carried out so far to measure concentrations of salivary nerve growth factor (NGF), including ours, have employed the same enzyme immunoassay kit (NGF Emax immunoassay system; Promega, Madison, WI). Following the withdrawal of the NGF Emax immunoassay from the market, we continued our investigation using other available ELISA kits. Surprisingly, we weren't able to detect the NGF peptide in any of the samples evaluated, and thus were unable to reproduce the data previously obtained with the NGF Emax immunoassay. Based on existing scientific literature we formulate a specific working hypothesis to explain our negative findings: in the oral compartment, pro-NGF is prevented from maturing into β-NGF. Finally, our suggestion to researchers who have published data on the role of NGF in various settings using Emax immunoassay kits, is to revise their data in light of the possibility that pro-NGF may have been the main acting character on stage. This article is protected by copyright. All rights reserved.
