Objectives: To explore the effect of IL-18 on peripheral blood monocytes (PBMCs) from chronic hepatitis B (CHB) patients and HBV DNA released by HepG2.2.15 cells, which were transfected with the gene of HBV.
Methods: PBMCs were isolated from 25 healthy persons and 25 CHB patients, which were co-cultured with HBcAg and IL-18 at different concentrations for 72 hours. The level of IFN-gamma in the culture supernatant of PBMCs was determined by ELISA. One patient' PBMCs were co-cultured for 96 hours with various concentrations of IL-18 and HepG2.2.15 cells which had been cultured for 24 hours, the supernatant was collected to detect HBV DNA level by PCR.
Results: When PBMCs were stimulated by HBcAg and IL-18 at various concentrations, the levels of supernatant IFN-gamma in the CHB group were much higher than those in the normal control group (at 0.2ng/ml: t=11.7, P<0.01; at 1.0ng/ml: t=16.19, P<0.01; at 5.0ng/ml: t=20.12, P<0.01), especially when the PBMCs were stimulated by HBcAg, IL-18 and IL-12 (1313.20pg/ml+-187.76pg/ml vs. 390.75pg/ml+-43.23pg/ml, t=23.94, P<0.01). The IFN-gamma level in the patients who were stimulated by HBcAg alone was much lower than the levels in the patients who were stimulated by HBcAg and IL-18 at various concentrations, and which were lower than those in the patients stimulated by HBcAg, IL-12 and IL-18 at the same concentrations (light: t=2.2, P<0.05; moderate: t=2.97, P<0.05). The HBV DNA content in the supernatant of co-cultivation with HepG2.2.15 cells and PBMCs was much higher than that of the two kinds of cells stimulated by HBcAg and IL-18 at various concentrations or HBcAg, IL-18 and IL-12/IFN-a1b.
Conclusion: IL-18 can improve the PBMCs from CHB patients to produce a great deal of IFN-gamma, so it has a good application prospect in two aspects: immunoregulatory effects and increasing the ability to kill the cells infected with virus.