Objective: The purpose of this study was to develop and evaluate a direct sandwich enzyme-linked immunosorbent assay (ELISA) for quantification of the lipoprotein lipase (LPL) immunoreactive mass in human plasma using monoclonal antibodies (MAbs) directed against LPL purified from human postheparin plasma (PHP) [corrected].
Methods and results: The direct sandwich-ELISA was performed using a combination of two distinct types of MAbs that recognize different epitopes on the LPL molecule. The immunoreactive mass of human LPL was specifically measured using a horseradish peroxidase-labeled anti-human LPL MAb [1(1)D2B2] as an enzyme-linked MAb, and an anti-human LPL MAb [2(10)F8F9] coated on a polystyrene microtiter plate as a solid-phase MAb. Purified human PHP-LPL was used as a standard material. The detection range of the sandwich-ELISA was 3.6-460 ng of LPL protein per mL of plasma. The intra- and interassay coefficients of variation were less than 5.9% and 3.3%, respectively. The validity of this method was additionally assured by the recovery test, which resulted in the variation only between 97.5% and 105.1%, and also by the interference test, which resulted in noninterference of LPL assay with a high concentration of triglyceride, hemoglobin, bilirubin, uric acid, or creatinine. To assess the reliability of the LPL mass values obtained with the direct sandwich-ELISA, they were compared with LPL mass values determined by the one-step sandwich-EIA (MARKIT-F LPL EIA kit) previously established by us. This comparison showed a highly significant correlation (r = +0.990) between the two sets of values. The LPL mass concentrations in PHP from 33 healthy subjects were 267 +/- 53 and 257 +/- 59 ng/mL (mean +/- SD), respectively.
Conclusion: The present direct sandwich-ELISA is useful for rapidly identifying certain abnormalities of LPL in PHP samples from patients with hypertriglyceridemia [corrected].