16 Genetic engineering has also been used to redirect effector T cell specificity, either by transduction with a T cell receptor (TCR)-specific for the immunodominant human leukocyte antigen A (HLA-A)*0201-restricted HBc18-27 epitope,17 or by expressing a chimeric antigen receptor.18 Despite extensive efforts, most immunotherapeutic approaches are not yet clinically relevant. In addition, selleck products their preclinical development is limited by a lack of in vivo models addressing their efficacy in the context of a human immune system.19
Surprisingly, plasmacytoid dendritic cells (pDCs), which are uniquely specialized in launching antiviral responses,20, 21 have not been used to stimulate antiviral responses against HBV. Due to their ability to detect the presence of single-stranded RNA and CpG-DNA and subsequently produce large quantities of type I IFN and induce adaptive immune responses, pDCs play a crucial role in immunity to viruses. pDCs can cross-present viral antigens following direct infection or after sensing infected
cells,22, 23 induce virus-specific adaptive immune responses in vitro,24 and also elicit cytotoxic T lymphocytes (CTLs) in vivo following Pirfenidone viral infection.25 Despite these outstanding properties, the potential of pDCs has not been harnessed to drive immunity against HBV. This is due in part to their scarcity and the difficulty of generating these cells from hematopoietic progenitors. If these difficulties could be overcome, pDCs would be a very promising means of restoring MCE HBV-specific immune responses. We developed a powerful tool in the form of a unique human HLA-A*0201+ pDC line that shares phenotypic and functional features of primary pDCs.26 This cell line has been used to promote immune responses toward viral- or tumor-specific antigens. The potential of irradiated peptide-loaded pDCs to induce antigen-specific responses in HLA-A*0201-matched settings has been shown to be effective in the context of melanoma27
as well as Epstein-Barr virus and cytomegalovirus infections.28 In the present study, we investigated the potential of pDCs in triggering functional antiviral cellular immunity against HBV ex vivo in a large cohort of chronic HBV patients and addressed their therapeutic potential in vivo using a Hepato-HuPBL mouse model. The results revealed that hepatitis B e antigen (HBeAg) is a key factor in inducing specific responses irrespective of overall clinical status. ALT, alanine aminotransferase; CFSE, carboxyfluorescein succinimidyl ester; CTL, cytotoxic T lymphocyte; HBcAg, hepatitis B core antigen; HBeAg, hepatitis B e antigen; HBsAg, hepatitis B surface antigen, HBV, hepatitis B virus; HLA-A, human leukocyte antigen A; IFN, interferon; LIL, liver-infiltrating lymphocyte; mDC, myeloid dendritic cell; PBMC, peripheral blood mononuclear cell; pDC, plasmacytoid dendritic cell; TCR, T cell receptor.