To purify CMVpp65495–503-specific CD8+ T cells, purified total CD8+ T cells from CMVpent+ subjects were stained with the biotin mAb cocktail for CD8+ T-cell isolation and subsequently with Streptavidin-PE and CMVpent-APC (Proimmune). CMVpent+ cells were sorted in a FACSAria to 95% purity. Human neonatal CD8+ T cells from UCBMC were labeled with anti-CD8 microbeads (Miltenyi) and purified using Estrogen antagonist POSELD2 program (purity of CD3+CD8+≥90%). Purified
CD8+ T cells were cultured (5×105 cells/mL) with medium alone (RPMI-glutamax medium (Invitrogen) supplemented with 10% FCS (Sigma) and 1% penicillin/streptomycin (Invitrogen)) or medium containing IFN-α2b, IFN-α5, anti-CD3/CD28-Beads (Beads coated with anti-human CD3 and CD28 mAb)
(Invitrogen) alone or together with IFN-α (IFN-α2b or IFN-α5). The IFN-α dose was 500 IU/mL. Beads were used at a 1:10 Beads:cell ratio. Purified CMVpp65495–503-specific CD8+ T cells were left unstimulated or stimulated with anti-CD3/CD28-Beads alone or together this website with IFN-α, in IL-2-conditioned medium (50 IU/mL) (Peprotech). In some cases, previously to stimulation, CD8+ T cells were labeled with 1.25 μM of CFSE (Sigma-Aldrich). In some cases, freshly purified CD8+ T cells were directly co-cultured (4 h) (i) with control IgG- or anti-CD3 OKT3 mAb-loaded p815 target cells (E:T ratio=10:1) or with (ii) HLA-A2+ T2 cells (E:T=5:1) loaded with HLA-A2-restricted control peptide (Leukocyte Proteinase-3169–177) or CMV peptide (Proimmune), in the presence or absence of IFN-α. To facilitate
IFN-γ detection by intracellular staining, cells were cultured in the presence of Brefeldin A (10 μg/mL) (Sigma-Aldrich) for the last 6 h of culture or along the culture (in the case of 4 h short-term assay). For the detection of CD107a, cells were cultured in the presence of anti-human CD107a-PE mAb (H4A3) or mouse IgG1-PE (10 μg/mL) (BD Biosciences) and Monensine (1 μg/mL) (Sigma-Aldrich). Total C-X-C chemokine receptor type 7 (CXCR-7) RNA was extracted using the nucleic Acid Purification lysis solution and the semiautomated ABI Prism 6100 Nucleic Acid PrepStation system (Applied Biosystems). Total RNA was treated with DNase prior to RT with M-MLV reverse transcriptase in the presence of RNaseOUT (all from Invitrogen). Real-time RT-PCR was performed using the CFX96 Real-time system, the IQ SYBR Green Mix (BioRad) and specific primers for each gene (Supporting Information Table 3). Results were normalized to β-actin. The amount of each transcript was expressed by the formula: 2Δct [Δct=ct(β-actin)-ct(gene], with ct as the point at which fluorescence rises appreciably above background fluorescence. Cells stained with fluorochrome-labeled mAb and/or CFSE were acquired on a FACSCalibur (BD Biosciences) and analyzed using FlowJo (Tree Star). Fold expansion was calculated as the output/input ratio of the absolute numbers of cells determined using Trucount beads (BD Biosciences).