Time-resolved Fluorescence Immunoassay (TRFIA) for the Simultaneous Detection of Hs-Crp and Lipoprotein(a) in Serum

Elevated serum high-sensitivity C-reactive protein (hs-CRP) and lipoprotein(a) (Lp(a)) levels are associated with the development of native coronary atherosclerosis. We aimed to establish a new method for the simultaneous detection of hs-CRP and Lp(a) to predict the development of atherosclerosis. A one- step time-resolved fluorescence immunoassay (TRFIA) with europium(III) (Eu3+) or samarium(III) (Sm3+) labelswas established, and the performance of this TRFIA (in terms of sensitivity, specificity, accuracy, and cutoff values) was evaluated using clinical serum samples and comparedwith those of registered kits. The sensitivity was 0.052 mu g/ml for hs-CRP and 0.64 mu g/ml for Lp(a). The intra-assay and inter-assay cross-reactivities (CVs) were very low, ranging from 2.05% to 4.67% for hs- CRP and from 2.42% to 6.43% for Lp(a). The CVs were very low (<0.34% and <2.65%, respectively) with five interferents. Additionally, there was a high Pearson coefficient between the present TRFIA method and the registered kits (R-2 = 0.9967 and 0.9906, respectively). These data indicate that this study developed a TRFIA method that can be used for the quantitative detection of hs- CRP and Lp(a) in serum with high sensitivity, specificity, and accuracy. This TRFIA provides a new method for predicting the development of atherosclerosis.