Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide with a poor prognosis and limited therapeutic options. To aid the development of novel immunological interventions, we studied the breadth, frequency, and tumor‐infiltration of naturally occurring CD8+ T‐cell responses targeting several tumor‐associated antigens (TAA). We used overlapping peptides spanning the entire alpha‐fetoprotein (AFP), glypican‐3 (GPC‐3), melanoma‐associated gene‐A1 (MAGE‐A1) and New York‐esophageal squamous cell carcinoma‐1 (NY‐ESO‐1) proteins and major‐histocompatibility‐complex‐class‐I‐tetramers specific for epitopes of MAGE‐A1 and NY‐ESO‐1 to analyze TAA‐specific CD8+ T‐cell responses in a large cohort of HCC patients. After nonspecific expansion in vitro, we detected interferon‐γ (IFN‐γ)‐producing CD8+ T cells specific for all four TAA in the periphery as well as in liver and tumor tissue. These CD8+ T‐cell responses displayed clear immunodominance patterns within each TAA, but no consistent hierarchy was observed between different TAA. Importantly, the response breadth was highest in early‐stage HCC and associated with patient survival. After antigen‐specific expansion, TAA‐specific CD8+ T cells were detectable by tetramer staining but impaired in their ability to produce IFN‐γ. Furthermore, regulatory T cells (Treg) were increased in HCC lesions. Depletion of Treg from cultures improved TAA‐specific CD8+ T‐cell proliferation but did not restore IFN‐γ‐production. Conclusion: Naturally occurring TAA‐specific CD8+ T‐cell responses are present in patients with HCC and therefore constitute part of the normal T‐cell repertoire. Moreover, the presence of these responses correlates with patient survival. However, the observation of impaired IFN‐γ production suggests that the efficacy of such responses is functionally limited. These findings support the development of strategies that aim to enhance the total TAA‐specific CD8+ T‐cell response by therapeutic boosting and/or specificity diversification. However, further research will be required to help unlock the full potential of TAA‐specific CD8+ T‐cell responses. (Hepatology 2014;59:1415‐1426)

We here present an immunologic head-to-head comparison between human umbilical cord lining mesenchymal stem cells (clMSCs) and adult bone marrow MSCs (bmMSCs) from patients >65 years of age. clMSCs had significantly lower HLA class I expression, higher production of tolerogenic TGF-β and IL-10, and showed significantly faster proliferation. In vitro activation of allogeneic lymphocytes and xenogeneic in vivo immune activation was significantly stronger with bmMSCs, whereas immune recognition of clMSCs was significantly weaker. Thus, bmMSCs were more quickly rejected in immunocompetent mice. IFN-γ at 25 ng/ml increased both immunogenicity by upregulation of HLA class I/ HLA-DR expression and tolerogenicity by increasing intracellular HLA-G and surface HLA-E expression, augmenting TGF-β and IL-10 release, and inducing indoleamine 2,3-dioxygenase (IDO) expression. Higher concentrations of IFN-γ (>50 ng/ml) further enhanced the immunosuppressive phenotype of clMSCs, more strongly downregulating HLA-DR expression and further increasing IDO production (at 500 ng/ml). The net functional immunosuppressive efficacy of MSCs was tested in mixed lymphocyte cultures. Although both clMSCs and bmMSCs significantly reduced in vitro immune activation, clMSCs were significantly more effective than bmMSCs. The veto function of both MSC lines was enhanced in escalating IFN-γ environments. In conclusion, clMSCs show a more beneficial immunogeneic profile and stronger overall immunosuppressive potential than aged bmMSCs.

Immunotherapies using cancer-testis (CT)antigensin 1 of these patients. These allogeneic immune responses were not detectable in pretransplantation samples and in the patients' stem cell donors, indicating that CT antigens might indeed represent natural targets for graft-versus-myeloma effects. Immune responses induced by alloSCT could be boosted by active CT antigen-specific immunotherapy, which might help to achieve long-lasting remissions in patients with MM.