Although promising, clinical responses to adoptive immunotherapy for nasopharyngeal carcinoma (NPC) are still limited by the restricted number of Epstein-Barr virus (EBV) antigens that can be targeted and their poor immunogenicity. Our previous work indicated that the immunogenic features of the NPC-associated viral antigen BARF1 may be exploited for immunotherapeutic purposes. Nevertheless, T-cell lines obtained with current protocols include only negligible numbers of BARF1-specific cytotoxic T-lymphocytes, pointing to the need to enrich these effectors in BARF1 specificities. Considering that in B-lymphocytes BARF1 is mainly a lytic EBV antigen, we investigated different EBV lytic cycle inducers (TPA/butyric acid, doxorubicin and cisplatin) used at suboptimal concentrations for their ability to up-regulate BARF1 expression in lymphoblastoid B-cell lines (LCLs), the commonly used antigen presenting cells, without compromising their survival. Our results demonstrate that LCLs treated with doxorubicin (DX-LCLs) can reproducibly and efficiently generate EBV-specific effectors enriched in BARF1 specificities from both healthy donors and NPC patients. Moreover, DX-LCLs also show more pronounced immunogenic properties, including HLA class I up-regulation and expression of immunogenic cell death markers such as enhanced calreticulin exposure and HMGB1 release. In particular, doxorubicin triggers an HMGB1 autocrine/paracrine loop with its TLR4 receptor, also up-regulated in DX-LCLs, responsible for NF-kB activation and a delayed apoptosis that allows a prolonged stimulation of EBV-specific T-cell precursors. This protocol may thus constitute a valid alternative to the use of engineered LCLs to generate EBV-specific T-cell lines for adoptive immunotherapy, being relatively simple, easily up-gradable to GMP standards and therefore more broadly applicable.
- Received April 17, 2015.
- Revision received December 22, 2015.
- Accepted February 7, 2016.
- Copyright ©2016, American Association for Cancer Research.