Related Experiment Video
Updated: Jan 9, 2026
Split Hybridization Probe Utilizing a DNA Fluorescent Light-up Aptamer as a Signal Reporter for Sequence-Specific Nucleic Acid Analysis
Published on: July 8, 2025
A solution for distinguishing Le(a-b-) sera in CA19-9 assays using SphereLight 180 and Architect i2000 assays
Hiroyuki Hanada1, Satomi Mugii, Keiko Takeoka
1Division of Laboratory for Clinical Investigation, Department of Medical Technology, Osaka University Hospital, Suita, Osaka, Japan. hanada@hp-lab.med.osaka-u.ac.jp
Background:
Measurement of carbohydrate antigen (CA) 19-9 is not applicable in patients with Lewis (Le) blood type, Le(a-b-). It is important to distinguish cases with Le(a-b-) before CA19-9 measurement. Therefore, we prepared a cut-off solution that gives a clear index to distinguish Le(a-b-) sera.
Method:
The frequencies of Le blood types and the distribution of the CA19-9 values in each Le blood type were examined in 188 healthy subjects. The CA19-9 values for all Le(a-b-) sera and for a portion of Le(a-b+) sera exist below the limit of quantitation as measured by the SphereLight 180 kit. The cut-off solution, which gives a clear cut-off index (COI), was prepared to differentiate Le(a-b-) from Le(a-b+), and was evaluated using the SphereLight 180, Architect i2000, UniCel DxI 800, Elecsys 2010, and Lumipuls ƒ kits.
Results:
The COI was calculated as the mean +3 SD of the CA19-9 values of a cut-off solution that is adjusted to the limit of detection. Both the sensitivities and specificities of the COIs were 100% using the SphereLight 180 kit and 100% and 91.7%, respectively, using the Architect i2000 kit, but these values were not satisfactory using the other CA19-9 assay kits.
Conclusion:
The COIs, determined by the cut-off solution, correctly identified all Le(a-b-) sera as Le(a-b-) and differentiated Le(a-b-) sera from other types of sera in CA19-9 assays using only the SphereLight 180 and Architect i2000 kits.
