Presentation of the HCV-derived lipopeptide LP20-44 by dendritic cells enhances function of in vitro-generated CD4+ T cells via up-regulation of TLR2

In vitro immunization with HCV lipopeptide aa 20-44 results in antigen-specific T cells. Here, we studied whether presentation of the lipopeptide by dendritic cells (DC) results in enhanced T cell functions. DC-immunized T cells showed significantly augmented proliferation and IFN-gamma secretion upon HCV-specific re-stimulation. This effect was related to significantly increased expression of TLR2 on DC-immunized CD4+ T cells and required TLR2 triggering during re-stimulation. In contrast, numbers of HLA-A2-pentamer-positive CD8+ T cells and granzyme B-secreting T cells remained unchanged. Thus, up-regulation of TLR2 during immunization with DC enhances functions of CD4+ T cells but not CD8+ T cells.