Effect of HRS cell line supernatant on LMP effector T-cell function and expansion of Treg cells in vitro. PBMCs from 5 different healthy subjects were cultured in supernatants from HRS cell lines (L1236, HDLM2, L428, L540) for 3 days (A-B). A fibroblast line supernatant and serum free culture media (SFCM) alone were used as negative controls. (C) An LMP2A peptide–specific IFN-γ ELISPOT assay following 3-day incubation of PBMCs (from a healthy HLA-A2 EBV-seropositive subject) with supernatant from the L540 HL cell line. Results are representative of 3 separate experiments. (D) T-cell reactivity toward CLG epitope (HLA-A2 restricted, LMP2A) in PBMCs from 2 different HLA-A2–positive individuals (D1 and D2) with or without depletion of CD4⁺ LAG-3⁺ T cells. Data from fresh PBMCs and PBMCs cultured in HRS cell supernatant are shown.