All the extracted cells from each liver biopsy were split in three wells and stimulated on the same day as PBMCs. 1610 6 PBMCs and liver-isolated cells were stimulated with either DMSO, HIV or HCV peptide pools as described previously [14] . HIV pools consisted of peptides that were screened by the matrix approach in that individual plus the HIV-Gag pool. Likewise, HCV pools consisted of mapped peptides plus an HCV pool that gave the strongest response in PBMCs. CD107a antibody (PE-Cy5, BD Pharmingen) was added at the time of stimulation. The following antibodies were used for staining: CD8-PE Texas-Red (Beckman Coulter), CD4-Pacific Blue (e-Bioscience), CD3-APCCY7, IFNc-FITC, TNFa-PECY7, IL2-APC, MIP-1b-PE (BD Bioscience), PD-1 FITC (Biolegend) and dead cell stain Aqua (Invitrogen, Molecular Probes).