Dual-label time-resolved immunofluorometric assay of serum AFP and AFP-IgM in patients with hepatocellular carcinoma

Objective: Serum alpha-fetoprotein (AFP) is a widely used marker of hepatocellular carcinoma (HCC), although its diagnostic efficacy remains to be improved. Elevated levels of immunocomplex form of AFP-IgM in HCC patients have been reported. In this study a novel dual-labeled time-resolved immunofluorometric assay (dual-TRFIA) was developed to measure serum AFP and AFP-IgM levels simultaneously in order to establish a more effective serum maker detection method for HCC. Methods: The du- al-TRFIA for AFP-IgM or AFP was established by using Sm3+-labeled anti-human IgM monoclonal antibody (McAb) and Eu3+-labeled anti-AFP MoAb as tracer antibodies. Serum AFP-IgM/AFP concentrations were measured in 118 patients with HCC, 60 patients with cirrhosis, 63 patients with chronic hepatitis and 286 healthy controls with the dual-TRFIA. The diagnostic efficacy was evaluated using receiver operating characteristic (ROC) curve. SAS 6.12 was used to analyze the data. Results: The lowest detective concentrations for AFP and AFP-IgM were 0.41 μg/L and 10.00 U/L, respectively. AFP concentrations determined with dual-TRFIA correlated well with those tested with electrochemiluminescence immunoassay (ECLIA) (r= 0.9987, P<0.05). The sensitivity for diagnosing HCC with serum AFP and AFP-IgM was 46.61% (55/ 118) and 63.56% (75/118), respectively. The area under the ROC curve for AFP and AFP-IgM was 77.10% and 77.40%, respectively. However, the diagnostic sensitivity increased to 72.88% (86/118) (χ2=9.45, P=0.02) and accuracy increased to 84.10% (χ2=6.24, P=0.04) when the two markers were combined. Conclusions: A highly sensitive and reliable dual-TRFIA for determination of serum AFP- IgM and AFP by a single test has been developed. It is suggested that combined measurement of serum AFP-IgM and AFP levels may improve the detection sensitivity of HCC. (authors)