To determine the presence of intra-hepatic viral specific T-cell responses, liver isolated cells were stimulated with HCV and HIV peptide pools. Summary data of viral specific responses are depicted in Figure 2 . In response to stimulation with HIV peptide pool, untreated co-infected individuals showed significantly higher frequencies of intra-hepatic CD4 + T-cells producing IFN-c, compared to HCV mono-infected [0.1660.05% vs 0.0260.01%, p,0.05], and HAART-treated co-infected individuals [0.1660.05% vs 0.0360.05%, p,0.05] (Figure 2a ). Untreated co-infected individuals showed a trend towards lower frequencies of intra-hepatic IFN-c producing CD4 + T-cells in response to HCV peptides. Surprisingly, HAART-treated co-infected individuals had significantly reduced HCV-specific IFN-c producing CD4 + T-cells when compared to untreated co-infected individuals [0.0260.01% vs 0.4660.11%, respectively, p,0.01] (figure 2a).