Simultaneous determination of alpha-fetoprotein immune complexes and alpha-fetoprotein concentration in hepatocellular carcinoma using dual-label time-resolved immunofluorometric assays.

Alpha-fetoprotein (AFP) is a commonly used tumor marker in the detection of hepatocellular carcinoma (HCC), and its sensitivity and specificity is insufficient to detect HCC in all patient samples. Recently, the immunocomplexed forms of AFP (AFP-IgM) have been reported to be present in HCC patients. This study was aimed at developing a novel time-resolved immunofluorometric assay (TR-IFMA) for the simultaneous determination of AFP-IgM and AFP concentration in HCC. We constructed a double-label assay by using Sm3+-labeled mAb to human IgM antibody, Eu3+-labeled mAb to AFP, and immobilized another mAb to AFP on the solid phase. The performances of the assay were all found to be satisfactory. The validity of the novel assay was confirmed by the good correlation between the results obtained by TR-IFMA and commercial ELISA or electrochemiluminescence immunoassay. AFP-IgM and AFP were increased above the cutoffs in 65.25 and 45.76% of HCC, respectively. ROC analysis yielded the following area under the curve: AFP-IgM 0.774 (CI 95% 0.736-0.809), AFP 0.771 (CI 95% 0.733-0.860). The combined use of AFP-IgM and AFP increased the sensitivity of detection to 72.88% in patients with HCC. These data suggest that the use of a combination of two markers in clinical practice could increase the accuracy of HCC diagnosis. Copyright 2009 Wiley-Liss, Inc.