Monoclonal antibody-based discrepancies between two-site immunometric tests for lutropin

Area of Science:

• Clinical Chemistry
• Endocrinology
• Immunodiagnostics

Background:

• Accurate measurement of lutropin (LH) is crucial for clinical diagnostics and research.
• Two-site immunometric assays are commonly used for LH quantification.
• Monoclonal antibodies targeting specific LH epitopes can influence assay performance.

Purpose of the Study:

• To compare the performance of five two-site immunometric assays for serum LH measurement.
• To evaluate the impact of monoclonal antibodies targeting the intact LH dimer on assay results.
• To identify potential discrepancies between immunoreactivity and bioactivity of LH.

Main Methods:

• Comparison of three commercially available and two in-house two-site immunometric assays for LH.
• Analysis of 83 serum samples, with a focus on 19 samples showing low LH concentrations.
• Assessment of LH bioactivity in five serum samples using in vitro methods.

Main Results:

• Four of the five assays, utilizing monoclonal antibodies against the intact LH dimer, reported significantly lower LH concentrations compared to a reference method.
• Two assays failed to detect significant LH immunoreactivity in five serum samples.
• The low immunoreactivity in these samples did not correlate with their normal in vitro LH bioactivity.

Conclusions:

• Monoclonal antibodies specific for the intact LH dimer can lead to underestimation of LH levels.
• These assays may fail to detect bioactive LH, causing confusion in clinical and research settings.
• The study recommends avoiding monoclonal antibodies specific for the intact LH dimer in LH assays.