Hbv core antigen

CD4⁺ T cells were enriched from PBMCs by positive selection using magnetic-activated cell-sorting columns (Miltenyi Biotec, Germany) and adjusted to a cell density of ~ 1 × 10⁶ cells/mL. Purified CD4⁺ T cells were stimulated for 72 h at 37 °C with HBV core antigen (1 μg/mL; Meridian, BioDesign, USA) + PBS (control; GIBCO, USA), HBV core antigen (1 μg/mL; Meridian, BioDesign, USA) + anti-IgG1 (1 μg/mL; eBioscience, USA), HBV core antigen + anti-PDL1 (1 μg/mL; eBioscience, USA), HBV core antigen + anti-LAG-3 antibody (1 μg/mL; Abcam, UK), and HBV core antigen + anti-PDL1 (1 μg/mL) + anti-LAG-3 antibody (1 μg/mL). Subsequently, the cell culture supernatants were collected and stored at − 80 °C for ELISA, and the cells were collected for flow cytometry.