Analysis of IFN-γ– or IL-4–producing HBenvAg-specific CD4⁺ T-cell frequencies.

PBMCs isolated from XLA patients (A) or control subjects (B) either before or after 1, 12, and 24 months from the immunization against HBV, were assessed by ELISPOT assay for their capacity to form IFN-γ or IL-4 spots in response to a 48-hour stimulation with 10 μg/mL HBenvAg. Responses by XLA patients' PBMCs at various antigen concentrations 1 month after vaccination appear in the inset and are expressed as mean ± SEM. Similar results were obtained in controls (not shown). Data are expressed as number of cytokine-producing CD4⁺ T cells in 1 × 10⁶total PBMCs. For each patient, solid triangles and circles represent IFN-γ– or IL-4–producing cells, respectively, in the presence of HBenvAg. Open triangles and circles represent the respective cytokine-producing cells in the absence of HBenvAg-stimulation. Pt indicates patient; Ct, control subject.