Establishment of interleukin-18 time-resolved fluorescence immunoassay and its preliminary application in liver disease.

Background To establish a time-resolved fluorescence immunoassay of interleukin (IL)-18 (IL-18-TRFIA) and detect its concentration in different liver disease serum samples. Methods The IL-18 coating antibody and the Eu3+ -labeled detection antibody were used for the IL-18-TRFIA to detect serum IL-18 concentration in patients with liver cancer, hepatitis B, hepatitis C, autoimmune hepatitis, fatty liver disease, and healthy controls. The double-antibody sandwich method was used and methodological evaluation was performed. Results The average intra- and inter-assay coefficient of variation for IL-18-TRFIA was 4.80% and 5.90%, respectively. The average recovery rate was 106.19 ± 3.44%. The sensitivity (10.96 pg/mL) was higher than that obtained using the ELISA method (62.5 pg/mL). The detection range was 10.96-1000 pg/mL. IL-6 and galectin-3 did not cross-react with IL-18-TRFIA. The serum concentration of IL-18 was (776.99; 653.48-952.39 pg/mL) in hepatitis C, (911; 775.55-1130.03 pg/mL) in fatty liver, (1048.88; 730.04-1185.10 pg/mL) in liver cancer, and (949.12; 723.70-1160.28 pg/mL) in hepatitis B. Moreover, IL-18 serum levels were significantly higher in patients than the healthy controls (483.09; 402.52-599.70/mL) (p 0.05). Conclusion We established a highly sensitive IL-18-TRFIA method that successfully detected serum IL-18 concentrations in different liver diseases. Furthermore, IL-18 serum concentration was higher in patients with liver cancer, hepatitis C, hepatitis B, and fatty liver disease compared to healthy controls.