Evaluation of commercial ELISA and RIA for measuring porcine C‐peptide: implications for research

Abstract

Porcine C-peptide concentration can be reliably measured in porcine serum samples with either assay (ELISA or RIA). However, the C-peptide results generated by these two assays are not equivalent. Therefore, assay bias must be considered before directly comparing pre-clinical studies that used either of these assays. We determined that harmonization between the assays is appropriate in a specific concentration range. Outside of that range, we do not know whether a linear correction function can be more broadly applied. The variation between the two assays may be related to calibration or reagent factors. To determine which assay is truly more accurate and to effectively compare interlaboratory results, we will need a traceable reference standard.

Cross‐validation of commercial enzyme‐linked immunosorbent assay and radioimmunoassay for porcine C‐peptide concentration measurements in non‐human primate serum

“…As we reported previously, a low bias was observed in the ELISA results using the RIA standards; conversely, a high bias was observed in the RIA results using the ELISA standards …”

“…Similarly, RIA data can be transformed, the slope was 0.4930±0.0456 (95% CI, 0.4882‐0.4977), and the intercept, −0.0456±0.0063 (95% CI, −0.0581 to −0.0332). Recommended correction factors to effectively harmonize comparisons between the previous RIA with the new ELISA in NHP serum matrix are presented in Table ; porcine matrix is presented for comparison …”

“…Validation studies were performed for both assays as previously described, with specific performance parameters defined prior to validation and outlined in Table…”

“…Mercodia introduced a PCP enzyme‐linked immunosorbent assay (ELISA) in 2011. We previously reported on the validation and comparison of these two PCP assays in porcine serum samples . PCP assays measure concentration as a component of efficacy evaluation, and therefore, the interest in validation is primarily scientific as opposed to the regulatory aspect of manufacturing or marketing biological products, which is different from bioassays used to drug use and patient safety (eg, drug exposure or binding assays).…”

Xenotransplantation literature update, January–February 2015

“…To determine the level of agreement between the RIA and enzyme‐linked immunosorbent assay (ELISA) that is available as a replacement, Graham et al. evaluated the serum C‐peptide concentrations in 60 landrace pigs at fasting and glucose challenge. The authors concluded that comparison of RIA and ELISA measurements of the same sample was not equivalent but within a linear range, the assays may correlate.…”