Dynamic visualization of the whole process of cytotoxic T lymphocytes killing B16 tumor cells in vitro.

Shuhong Qi,Zhihong Zhang,Lei Liu,Hua Shi,Lili Zhou

doi:10.1117/1.jbo.24.5.051413

Abstract

.Cytotoxic T lymphocytes (CTLs) play a key role in adoptive cell therapy (ACT) by destroying tumor cells. Although some mechanisms of CTLs killing tumor cells have already been revealed, the precise dynamic information of CTLs’ interaction with tumor cells is still not known. Here, we used confocal microscopy to visualize the whole process of how CTLs kill tumor cells in vitro. According to imaging data, CTLs destroyed the target tumor cells rapidly and efficiently. Several CTLs surrounded one or more tumor cells, and the average time for CTLs destroying one or more tumor cells in vitro is dozens of minutes only. Our study displayed the temporal events of CTLs’ interaction with tumor cells at the beginning up to the point of killing them. Furthermore, the imaging data presented strong cytotoxicity of CTLs toward the specific tumor cells. These results could help us to well understand the mechanism of CTLs’ elimination of tumor cells and improve the efficacy of ACT in cancer immunotherapy.

Highlights

Cancer immunotherapy, including the use of monoclonal antibodies, tumor vaccines, checkpoint blockade therapy, and adoptive cell therapy (ACT), is considered a breakthrough in cancer therapy.[1,2,3] ACT is reportedly one of the most efficient therapeutic strategies for melanoma treatments.[4]
The study demonstrated that the multicolor dynamic imaging of Cytotoxic T lymphocytes (CTLs) and tumor cells could become an effective and easy-to-operate method to assess the abilities of CTLs before ACT immunotherapy for cancer treatment
The CTLs successfully killed most of the Cyan fluorescent protein (CFP)-B16 tumor cells, and the survival percentage of CFP-B16 decreased to 8.5%

Summary

Introduction

Cancer immunotherapy, including the use of monoclonal antibodies, tumor vaccines, checkpoint blockade therapy, and adoptive cell therapy (ACT), is considered a breakthrough in cancer therapy.[1,2,3] ACT is reportedly one of the most efficient therapeutic strategies for melanoma treatments.[4]. When meeting a tumor cell, T-cell receptors (TCRs) expressed on the CTLs could recognize specific tumor antigens on the tumor cell and induce its cytotoxic response.[5] The mechanisms of CTLs killing tumor cells unfold in several ways: through the secretion of perforin and granzyme B, through the interaction of FasL and Fas on the cell surface, and through the NKG2D pathway.[6,7,8,9,10] Before ACT, the activity and cytotoxicity of CTLs against target tumor cells need to be evaluated in vitro. Even though these methods revealed some important facts about CTLs’ killing abilities, other dynamic details, especially the special interaction between CTLs and target tumor cells and the whole process of CTLs successfully killing tumor cells are still not well understood.[7,8,9,11,12,13]

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Discussion

Conclusion