American Association for Cancer Research
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Supplementary Movie 2 from Committing Cytomegalovirus-Specific CD8 T Cells to Eliminate Tumor Cells by Bifunctional Major Histocompatibility Class I Antibody Fusion Molecules

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posted on 2023-04-03, 23:09 authored by Martina Schmittnaegel, Victor Levitsky, Eike Hoffmann, Guy Georges, Olaf Mundigl, Christian Klein, Hendrik Knoetgen

Time-lapse fluorescence microscopy of CMV-pp65-specific T cell mediated killing of MCSP+ tumor cells (Colo38) incubated with 15nM of EBV-pMHCI-IgG as control. Constructs are indicated in the respective panel. T cells are stained in red (PKH-26, Sigma), tumor cells in green (CMFDA, LifeTechnologies). Effector to target ratio was 3:1. Real-time is indicated in the lower left corner in h:m:s:ms (h=hours, m=minutes, s=seconds, ms=milliseconds), scale bar is shown in the lower right corner 0-50 µm (µm=micrometre).



Tumor cells escape immune eradication through multiple mechanisms, including loss of antigenicity and local suppression of effector lymphocytes. To counteract these obstacles, we aimed to direct the unique cytomegalovirus (CMV)-specific immune surveillance against tumor cells. We developed a novel generation of fusion proteins composed of a tumor antigen–specific full immunoglobulin connected to a single major histocompatibility class I complex bearing a covalently linked virus-derived peptide (pMHCI–IgG). Here, we show that tumor antigen–expressing cancer cells, which are decorated with pMHCI–IgGs containing a HLA-A*0201 molecule associated with a CMV-derived peptide, are specifically eliminated through engagement of antigen-specific CD8+ T cells isolated from peripheral blood mononuclear cell preparations of CMV-infected humans. These CD8+ T cells act without additional expansion, preactivation, or provision of costimulatory signals. Elimination of tumor cells is induced at similar concentrations and with similar time kinetics as those seen with bispecific T-cell engagers (BiTE). However, while BiTE-like reagents indiscriminately activate T cells through binding to the T-cell receptor complex, pMHCI–IgGs selectively engage antigen-specific, constantly renewable, differentiated effector cytotoxic T lymphocytes to tumor cells, thereby representing a novel class of anticancer immunotherapeutics with potentially improved safety and efficacy profiles. Cancer Immunol Res; 3(7); 764–76. ©2015 AACR.

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