In vitro Generation of Cytotoxic T Cells With Potential for Adoptive Tumor Immunotherapy of Multiple Myeloma.

Wafaa S Khalaf,Mamta Garg,Michael J Browning,Yehia S Mohamed,Cordula M Stover

doi:10.3389/fimmu.2019.01792

Abstract

Multiple myeloma is a life-threatening hematological malignancy, which is rarely curable by conventional therapies. Immunotherapy, using tumor antigen-specific, cytotoxic T-lymphocytes, may represent an alternative or additional treatment for multiple myeloma. In this study, we used hybrid cell lines, generated by fusion of an EBV B-lymphoblastoid cell line (B-LCL) and myeloma cells, to stimulate in vitro peripheral blood lymphocytes (PBLs) from patients with multiple myeloma. We investigated induction of antigen-specific, cytotoxic T-lymphocytes to the well-defined tumor associated antigens (TAAs) hTERT, MUC1, MAGE-C1 and CS1, which have been shown to be expressed in a high proportion of cases of multiple myeloma. HLA-A2-peptide pentamer staining, interferon-γ and perforin ELISpot assays, as well as cytotoxicity assays were used. Following several rounds of in vitro stimulation, the hybrid cell lines induced antigen-specific, cytotoxic T-lymphocytes to four candidate TAAs in PBLs from HLA-A2+ multiple myeloma patients, using known HLA-A2 restricted peptide epitopes of the TAAs. In contrast, the HLA-A2+ myeloma cell line U266 failed to induce antigen-specific, cytotoxic T-lymphocytes in vitro. Our data indicate that B-LCL/myeloma hybrid cell lines induce antigen-specific, cytotoxic T-lymphocytes in PBLs isolated from multiple myeloma patients in vitro and may represent a novel strategy for use in adoptive immunotherapy of multiple myeloma.

Highlights

Using conventional therapies, multiple myeloma (MM) is an incurable condition
We have shown that in vitro co-culture of Peripheral blood mononuclear cells (PBMCs) with hybrid cell lines resulted in the induction and expansion of tumor antigen-specific T cells with cytotoxic and IFN-γreleasing activity against a range of relevant tumor associated antigen (TAA) expressed by myeloma cells (MUC1, hTERT, CS1, MAGE C1)
Our study demonstrates the ability of hybrid cell lines, formed by fusion of HMy2 cells and myeloma cells, to induce antigen specific cytotoxic T cells in vitro among peripheral blood lymphocytes (PBLs) obtained from HLA A2+ patients with multiple myeloma

Summary

Introduction

Multiple myeloma (MM) is an incurable condition. Adoptive T cell therapy, drawing on allogeneic or autologous tumor-specific cytotoxic T-lymphocytes (CTL), may represent a potential additional treatment for MM. Hybrid cell lines, generated by fusion of professional antigen presenting cells (APC) with tumor cells, make for a promising strategy for tumor immunotherapy [1, 2]. Such cell lines express a range of tumor associated antigen (TAAs) and present these in the context of both HLA class I and HLA class II molecules, with appropriate costimulatory signals [1, 2]. The use of allogeneic APCs in hybrid cell formation may lead to the expression of allogeneic MHC class I aside from MHC class II by the generated hybrid cells, which exerts a desirable adjuvant effect on the stimulation of antigen-specific T lymphocytes [3].

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Results

Discussion

Conclusion