Abstract 4797: Dendritic cells loaded with autologous tumor lysate by electroporation effectively induce lysate specific IFN-γ producing T cells in glioblastoma patients Free

Electroporation (EP) can facilitate antigen uptake by dendritic cells (DCs) with consequently enhanced antigen processing and presentation. Earlier we reported that DCs electroporated in the presence of tumor lysate are fivefold to 20-fold more effective in proliferation of tumor-lysate-specific T lymphocytes compared to controls, DCs incubated with the same lysate. In this study we examined the ability of EP-loaded DCs to induce tumor-lysate-specific IFN-γ producing T cells. DCs were prepared from peripheral CD14-positive monocytes by culturing and maturating in culture medium containing GM-CSF, IL-4, PGE₂ and TNF-α. We electroloaded DCs from four glioblastoma patients who had been surgically treated. in the presence of autologous tumor lysates (final concentration of 2 mg/mL). In some experiments, we added zoledronate in the culture medium during DC maturating process in order to examine its enhanced effect on the induction of tumor-lysate-specific IFN-γ producing T cells. At 1.5 hrs after EP, we assessed such DCs’ ability to stimulate and proliferate T cells in comparison with DCs co-cultured with the same tumor lysate as control. We incubated autologous peripheral blood lymphocytes (1×10⁶) with lysate-loaded DCs (1×10⁵) for 14 days with IL-2 replenished every two to three days. Surface markers for T cell subsets were analyzed by flow cytometry on days 7 and 14 and IFN-γ secreting T cells by ELISPOT on day 14. EP-loaded DCs induced more IFN-γ producing T cells than control DCs (p<0.001). In two patients (Patient #2 & #3) that expressed higher levels of HLA class I molecules in resected tumor tissue, especially, IFN-γ producing T cells were tumor specific because such T cells significantly higher induced compared with DCs without lysate (p<0.001). Addition of zoledronate, further increased the induction of tumor lysate specific IFN-γ producing cells, concurrent to correlative expansion of the gamma-delta T cells in culture. We hypothesize that the gamma-delta T cells may play important roles in enhancement of tumor lysate specific IFN-γ producing cells. These results suggest that DCs electro-loaded with autologous tumor lysate in combination with zoledronate treatment induce more effective immune responses and may lead to development of more effective immunotherapies for treatment of glioblastoma patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4797.