Critical comparison of
ELISA
kits for
CGRP
measurements in migraine
Lucía de la Guerra‐Sasián, Vicente González‐Quintanilla, Jorge Madera, Sara Pérez‐Pereda, Julio Pascual, María Muñoz‐San Martín Abstract
Objectives/Background
Our aim was to compare the performance of commercially available enzyme‐linked immunosorbent assay (ELISA) kits for detecting mature α‐ and β‐calcitonin gene‐related peptide (CGRP) isoforms and test the hypothesis of a potential lack of reliability. CGRP is one of the most extensively studied biomarkers in migraine, but the reliability of commercially available ELISA assays for its measurement remains controversial.
Methods
In this method comparison study, we analyzed serum samples from 19 patients with migraine in Marqués de Valdecilla University Hospital, along with synthetic peptide samples (α‐ and β‐CGRP), including preparations of each isoform at different concentrations. The following ELISA kits were evaluated according to the manufacturers' instructions: one kit theoretically specific for α‐CGRP (abx252189, Abbexa, Kit B); and three kits considered specific for β‐CGRP (CSB‐E08210h, CUSABIO, Kit C; abx151047, Abbexa, Kit D; and abx514274, Abbexa, Kit E). In addition, Bertin assay (A05481.96), Kit A, designed to detect both CGRP isoforms, was assessed.
Results
Kit A was the only kit capable of detecting the synthetic peptide in both isoforms and demonstrated a measurable positive relationship of nominal versus observed levels. In contrast, the remaining kits, theoretically specific for a single isoform, failed to detect the corresponding synthetic peptide. Quantification of CGRP levels in 19 patient samples showed no significant correlation among the assays. No correlation was found among the three different assays targeting β‐CGRP. Intrakit variability was acceptable for all kits tested.
Conclusion
These findings indicate that the ELISA assays tested, designed to measure specific isoforms of mature CGRP isoforms, are unable to detect the synthetic peptide. Nevertheless, it is possible that these assays quantify other CALCA/CALCB ‐derived products that may retain biological activity in patients with migraine. The absence of correlation among kits targeting the β‐CGRP isoform further suggests differences among kits, which might be due to differences in calibration, cross‐reactivity, noise, or the use of different antigens, raising the possibility that the kits detect different CGRP‐related forms, including precursor/propeptide and other processed forms.