Mono-OKT3-Fab enhances recall T-cell expansion to NLV:HLA-A2. (A-D) PBMCs were cultured with or without exogenous NLV peptide in the presence of mono-OKT3-Fab or control Ms-IgG-Fab. (A) On day 9, cells were analyzed by flow cytometry for the number of A2/NLV-tetramer(+) CD8 T cells from exog-NLV-bulk-responsive donors (mean ± SD, 2-tailed paired Student t test). Mono-OKT3-Fab increased the production of IFN-γ (B) and granzyme B (C), as measured by ELISA of day 7 supernatants (mean ± SD, 1-tailed paired Student t test). Each symbol represents the average of ≥3 independent experiments per donor (A-C). (D) CD8 T-cell isolates (effectors) were cultured at the indicated effector to target ratios with NLV-loaded CD4 T cells (targets) overnight and analyzed for specific lysis of targets (mean ± SD of duplicates).