Analysis of MR and ME T-cell functions.

MR T cells were distinguished from ME T cells on the basis of the presence or absence of CD27 on the cell membrane. Cell function was evaluated in terms of production of IFN-γ after stimulation with HBenvAg, 10 μg/mL (solid bars) or 1 μg/mL (gray bars), or in terms of production of IL-4 after stimulation with HBenvAg, 10 μg/mL (open bars) or 1 μg/mL (coarse bars); production was determined at the single-cell level by ELISPOT assay. Data are expressed as the number of cytokine-producing cells in 1 × 10⁶ total PBMCs. At 24 months after the vaccination protocol was completed, PBMCs were isolated from XLA patients or control subjects and then tested in either unfractionated or purified form according to CD2 expression (of T cells) and subsequently enriched with, or depleted of, CD27⁺ cells as described in “Patients, materials, and methods.” The different cell populations were assayed 4, 18, 48, and 96 hours after culture in the presence of HBenvAg. Results obtained from 1 out of 2 XLA patients (Pt 1) and 1 out of 2 healthy subjects (Ct 1) are shown. Similar results were obtained in the other 2 individuals.