A comparison of commercial assays quantifying mature brain-derived neurotrophic factor (mBDNF) and its precursor (pro-BDNF) in human serum

Brain-derived neurotrophic factor (BDNF) and its isoforms (pro- and mBDNF) are promising neurobiomarkers. While total serum BDNF levels have been previously validated, the newer isoforms have not. We aimed to identify the most common serum pro- and mBDNF assays through a literature search (MEDLINE/PubMed, until March 2024), and to compare their methodological performance in 23 human serum samples [total BDNF: R&D Systems, #DBNT00; both isoforms: R&DSystems (#DY3175, #DBD00); Aviscera-Bioscience (#SK00752-09, #SK00752-01); FineTest (#EH4255, #EH0043)]. Western-blot and cross-reactivity assays were used to confirm whether the kits tested for the declared isoforms. The total BDNF (#DBNT00) and pro-BDNF (#DY3175) ELISA kits from R&D Systems, and the pro-BDNF ELISA kits from FineTest (#EH4255) and Aviscera-Bioscience (#SK00752-01) showed high specificity, sensitivity, accuracy, and reproducibility. None of the commercial brands tested for mBDNF quantification showed optimal specificity, although R&D Systems (#DBD00) showed an acceptable result. Additionally, comparison of serum mBDNF levels by direct measurement and estimation (total minus pro-BDNF) using the three R&D Systems kits in the 23 serum samples showed acceptable variation (± 15%). This work indicated that there is a need to continue improving the specificity of some ELISA kits, mainly those measuring mBDNF. Total, pro- and m-BDNF serum levels can be quantified using the R&D Systems kits, whereas pro-BDNF serum levels could, in principle, be measured using any of the three brands evaluated.