Simultaneous measurement of plasma concentrations of proinsulin and C-peptide and their ratio with a trefoil-type time-resolved fluorescence immunoassay.
| Autor: | De Pauw PE; Diabetes Research Center, Brussels Free University, Brussels, Belgium., Vermeulen I, Ubani OC, Truyen I, Vekens EM, van Genderen FT, De Grijse JW, Pipeleers DG, Van Schravendijk C, Gorus FK |
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| Jazyk: | angličtina |
| Zdroj: | Clinical chemistry [Clin Chem] 2008 Dec; Vol. 54 (12), pp. 1990-8. Date of Electronic Publication: 2008 Oct 09. |
| DOI: | 10.1373/clinchem.2008.109710 |
| Abstrakt: | Background: When the concentrations of 2 or more substances are measured separately, their molar ratios are subject to the additive imprecisions of the different assays. We hypothesized that the cumulative error for concentration ratios of peptides containing a common sequence might be minimized by measuring the peptides simultaneously with a "trefoil-type" immunoassay. Methods: As a model of this approach, we developed a dual-label time-resolved fluorescence immunoassay (TRFIA) to simultaneously measure proinsulin, C-peptide, and the proinsulin-C-peptide ratio (PI/C). A monoclonal antibody captures all C-peptide-containing molecules, and 2 differently labeled antibodies distinguish between proinsulin-like molecules and true C-peptide. Results: The trefoil-type TRFIA was capable of measuring plasma C-peptide and proinsulin simultaneously without mutual interference at limits of quantification of 48 and 8125 pmol/L, and 2.1 and 197 pmol/L, respectively. Within-laboratory imprecision values for the trefoil-type TRFIA ranged between 8.4% and 12% for the hormone concentrations. Unlike the hormone results obtained with separate assays, imprecision did not increase when PI/C was calculated from trefoil assay results (P < 0.05). Peptide concentrations were highly correlated with results obtained in individual comparison assays (r(2) > or = 0.965; P < 0.0001). The total error for PI/C obtained with the trefoil-type TRFIA remained < or = 25% over a broader C-peptide range than with separate hormone assays (79-7200 pmol/L vs 590-4300 pmol/L C-peptide). Preliminary data indicate little or no interference by heterophile antibodies. Conclusions: The developed trefoil-type TRFIA is a reliable method for simultaneous measurement of proinsulin, C-peptide, and PI/C and provides proof of principle for the development of other trefoil-type multiple-label immunoassays. |
| Databáze: | MEDLINE |
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