Impedance-Based Label-Free Real-Time Cytotoxicity Assay

As a leader and expert in the field of gamma delta (γδ) T cell development, Creative Biolabs provides state-of-art cytotoxicity testing technologies to meet any requirement of our customers. We have completed a series of challenges in the past years. In particular, we have established an advanced impedance-based label-free real-time cytotoxicity assay which enables us to offer a series of high-quality services for determining the cytotoxicity of various γδ T cells.

Introduction to γδ T Cells

γδ T cells are a key group of unique T lymphocytes that can recognize a diversity of antigens in a major histocompatibility complex (MHC) unlimited manner. Nowadays, a range of surface antigens of γδ T cells, including CD16, ULBP, and CD56, has been confirmed. For example, previous studies have shown that phosphoantigens can be used as effector cells to activate γδ T cells and thus produce CD16-expression of circulating Vγ9Vδ2 T cells. Meanwhile, the results have suggested that these effector cells play an important role in treating malignant tumors. Moreover, this antigen recognition process of γδ T cells is critical to produce cytokines, regulate inflammation, remove pathogens, as well as maintain tissue homeostasis in stress response.

However, many human γδ T cell functions and phenotypes in various pathologies are still unclear. It is important to generate a full range of cell-based assays for identifying potential cell toxic liabilities based on both in vitro and in vivo analysis testing. These assays are usually designed by counting the cell death or detecting the uptake of a specific dye. Meanwhile, they can only measure the data derived from one or two time points, and it is not possible to early or late toxic events. As a result, many impedance-based label-free real-time cytotoxicity assays have been generated to continuously monitor target cells by using electronic sensors.

Fig.1 Cytotoxicity assay using a real-time cell analysis system. (Türker, 2017)

Our Impedance-based Label-free Real-Time Cytotoxicity Assay

Recent studies have revealed that the γδ T cell cytotoxicity test can be used as an attractive tool to estimate the safety of a number of γδ T cells or their treatments. Creative Biolabs has generated, modified, and regulated many advanced technologies to meet the requirement of γδ T cell cytotoxicity study. On this basis, we have developed a panel of standard techniques for assessing the capability and toxicity of different types of γδ T cells, including but not limited to, chromium-51 release assay, Europium-TDA assays, flow cytometry, as well as MTT assays. These methods are end-point assays based on the labeling of various distinct subsets of γδ T cells and share many limitations.

As a consequence, Creative Biolabs has developed an impedance-based label-free real-time cytotoxicity assay for measuring γδ T cell-mediated antibody-independent (AIC) and antibody-dependent cellular cytotoxicity (ADCC). In principle, when tumor cells are attached to the bottom of the perforated plate electrode, the isolation characteristics of the cell body add the impedance of the current. Killing these tumor cells leads to separation or disintegration, and thereby reducing the electrical impedance of the detection system, which can be finally measured by our data analysis system. For instance, the lysis kinetics has been evaluated by this assay in both primary and expanded γδ T cells y using a CD19 antibody alone and a CD19–CD16 bi-specific antibody. The data suggest that our assay is accurate, sensitive and can allow monitoring of the cleavage kinetics of γδ T cells over long periods.

Fig.2 Dynamic monitoring of expanded γδ T cell-mediated AIC and ADCC. (Seidel, 2014)

With years of operational experience, Creative Biolabs offers the best services for γδ T cells projects. Now, we have developed efficient protocols for impedance-based label-free real-time cytotoxicity assay. And we can also conduct custom in vitro studies to meet any requirements of our clients. If you have any special needs in our γδ T cell development services or be interested in learning more about our company, please feel free to contact us for more details.

References

1. Türker, Ş. L., et al. iCELLigence real-time cell analysis system for examining the cytotoxicity of drugs to cancer cell lines. Experimental and therapeutic medicine. 2017, 14(3): 1866-1870.
2. Seidel, U. J. E., et al. γδ T cell-mediated antibody-dependent cellular cytotoxicity with CD19 antibodies assessed by an impedance-based label-free real-time cytotoxicity assay. Frontiers in immunology. 2014, 5: 618.