Background

Immunotherapies for cancer treatment are rapidly emerging, and many studies aim at increasing the safety and efficacy of anti-tumor immunotherapies. More research is being conducted on natural killer (NK) cells, as they have minimal risk of causing neurotoxicity in autologous settings (Gong et al., 2021), graft-versus-host disease in allogenic settings (Du et al., 2021), or cytokine release syndrome in general (Du et al., 2021). Other than being relatively safe in treatment, NK cells are effective in direct killing of target cells and regulating the immune system (Vivier et al., 2011).

Antibody-dependent cellular cytotoxicity (ADCC) is an adaptive immune response largely mediated by NK cells through their CD16 (FCγRIII) receptor, which binds the Fc portion of IgG antibodies (Alderson and Sondel, 2011). However, this important aspect of NK cells remains underexplored. This can be ascribed to difficulties in establishing assay platforms. Previous protocols of ADCC assays use complex cell-based antigen-antibody models, such as the combination of SCC-4 cells and cetuximab (Kohrt et al., 2014), which is costly due to the low productivity of clinically relevant monoclonal antibodies, such as cetuximab. These target cell-based experiments also take a minimum of three days due to the need of culturing and maintaining target cells. The use of anti-CD16 antibody-opsonized P815 cells in reverse ADCC assays also evaluates NK cells ADCC (Euchner et al., 2021), but likewise requires time to culture and maintain the target cells.This current protocol is devoid of target cells, and uses plate-bound immobilized anti-CD16 antibodies as the trigger. Major steps include coating the plate with CD16 antibodies, preparing, and seeding the cells. It greatly shortens the experimental time to about 10 h, while faithfully evaluating NK cells ADCC. It can be used to quickly evaluate the ADCC aspect of any NK cell-based therapy product in vitro before subsequent in vivo testing, to facilitate the research and development (R&D) processes.