Toll-like receptor (TLR) expression on CD4+ and CD8+ T-cells in patients chronically infected with hepatitis C virus

Toll-like receptor (TLR) expression on T-cells and the signalling pathways that lead to the production of cytokines may limit antigen-specific T-cell responses. Here, expression of TLR and retinoic acid inducible gene I (RIG-I) on T-cells were evaluated in patients chronically infected with hepatitis C virus (HCV), before and during pegylated interferon-alpha and ribavirin therapy. Expression of TLR2,3,4,7,9 and retinoic acid inducible gene (RIG)-I on different CD4(+) and CD8(+) T-cell sub-populations (naïve: CD45RA(+)CD57(-); central memory: T(CM) CD45RA(-)CD57(-); effector memory: T(EM) CD45RA(-)CD57(+) and terminally differentiated effector memory: T(EMRA) CD45RA(+)CD57(+)) were measured by flow cytometry. TLR7, TLR9 and RIG-I expression on CD4(+) T-cells and RIG-I expression on CD8(+) T-cells was higher in patients than healthy controls. Therapy increased expression of TLR2, TLR4 and TLR9 and this was observed for all T-cell sub-populations. Evaluation of TLR expression at baseline did not identify patients able to achieve sustained virological response following therapy.