Validation and quality control of ELISAs for the use with human saliva samples

Enzyme-linked immunosorbent assays (ELISAs) have proven to be a powerful tool for fast and reliable sample analysis, in both clinical diagnostics and in research. Most assays are now available for use with a range of different analytical fluids, including serum, plasma or urine. In recent years, saliva has drawn attention as a potentially valuable diagnostic fluid; however few ELISAs have been validated for use with saliva, or their validation is often incomplete. Saliva has a number of different physical characteristics than, for example, cell culture medium or serum and assuming an ELISA which works well with serum samples will also do so with saliva potentially could lead to erroneous data and conclusions. In this report, we provide a detailed protocol to validate any ELISA for use with saliva samples and show the results of validation procedures for 13 ELISAs for using saliva. Our findings suggest that the majority of ELISAs work reliably with saliva, even if the assay was not specifically designed for this biological fluid. However, we also report a few cases where recovery or intra-and inter-assay variations were unexpectedly high, emphasising the importance of performing a validation procedure for each assay before using it with saliva to ensure accurate and reliable data.