Work

Activation of LMP1- and LMP2-specific T-cells for the immunotherapy of EBV positive malignancies with an adenoviral vector encoding full length LMP1 and LMP2

Year: 2006

Type: article

Abstract: Background: LMP1 and LMP2 are potential targets for the immunotherapy of EBV-positive malignancies such as nasopharyngeal carcinoma (NPC) and Hodgkin’s disease (HD). We have shown in the past that LMP1- and LMP2-specific T-cells can be activated from EBV-seropositive individuals with adenoviral vectors encoding either an inactive form of LMP1 (dLMP1) or LMP2. The aim of this study was to construct and characterize an adenoviral vector containing dLMP1 and LMP2 (Ad_dLMP1-I-LMP2) for the generation of LMP1- and LMP2-specific T cells. Methods: To evaluate the activity of Ad-dLMP1-I-LMP2 to reactivate LMP1- and LMP2-specific CTL, we took advantage of the tropism of Ad5F35 adenoviral vectors, which preferentially transduce monocytes after incubation of peripheral blood mononuclear cells (PBMC). Transduced monocytes expressed LMP1 and LMP2, and reactivated LMP1- and LMP2-specific T cells, that could be expanded further with autologous LCL transduced with Ad-dLMP1-I-LMP2. The presence of LMP1- and LMP2-specific CTL was determined by tetramer analysis, IFN-γ ELISPOT assays and cytotoxicity assays. Results: Stimulation of PBMC with Ad-dLMP1-I-LMP2 transduced monocytes from 10 HLA-A2, EBV-seropositive donors resulted in an at least 30 to 100 fold expansion of LMP1- or LMP2-specific T-cells as judged by the presence of HLA-A2 restricted, tetramer positive T-cells. LMP2-specific responses were detected in all donors where as LMP1-specific responses were found in 7/10 donors. The presence of LMP1- and LMP2-specific T-cells was confirmed in a subset of donors with IFN-γ ELISPOT assays. In addition, generated LMP1- and LMP2-CTL killed autologous fibroblasts expressing LMP1 and LMP2, as well as LCL. Conclusion: The constructed adenoviral vector, Ad-dLMP1-I-LMP2, is a promising candidate for the ex vivo generation of LMP1- and LMP2-specific CTL and may also be used as a vaccine for the in vivo boosting of adoptively transferred T cells. Targeting the subdominant LMP antigens expressed in NPC and HD may improve the efficacy of adoptive immunotherapy approaches.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2005.11.054