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Updated: Jun 19, 2026
Using Reference Reagents to Confirm Robustness of Cytokine Release Assays for the Prediction of Monoclonal Antibody Safety
Published on: September 15, 2023
The analytical specificity of human chorionic gonadotropin assays determined using WHO International Reference
JoDell Whittington1, Corinne R Fantz, Ann M Gronowski
1University of Utah Health Sciences Center, Department of Pathology, Salt Lake City, UT 84108, USA.
Background:
Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone with considerable molecular heterogeneity. There is uncertainty regarding which hCG variants are detected by different hCG assays. The analytical specificity of 8 hCG assays was investigated.
Methods:
WHO International Reference Reagents for hCG, nicked hCG (hCGn), beta subunit (hCGbeta), nicked beta subunit (hCGbetan), and beta core fragment (hCGbetacf) were individually added to hCG-free human serum. Specimens were analyzed with 8 commercially available hCG assays. Equimolar detection of hCG variants was defined as a recovery of 90-110%.
Results:
All assays detected hCG and hCGn with mean recoveries of 98.3 and 94.6%, respectively. Seven assays detected hCGbeta (mean recovery 103.8%) but with high variation, and equimolar detection was observed only in four. The mean recovery of hCGbetan was 85.5% but was highly variable with only two assays showing equimolar detection. With a mean recovery of 53.4%, two assays detected hCGbetacf and both underestimated it considerably. Information provided by the assay manufacturer regarding hCG variant analytical specificity was inadequate or unclear in 75% of the assays.
Conclusions:
hCG assays vary considerably in their ability to detect different hCG variants. Manufacturers of hCG assays should clearly indicate the hCG variant specificity of their reagent systems.
