NK Cytotoxicity Mediated by NK-92 Cell Lines Expressing Combinations of Two Allelic Variants for FCGR3

SUMMARY

Natural killer (NK) cells play an important role in the surveillance of viral infections and cancer. NK cell antibody-dependent cellular cytotoxicity (ADCC) and direct cytotoxicity are mediated by the recognition of antibody-coated target cells through the Fc gamma receptor IIIA (FcγRIIIa/CD16) and by ligands of activating/inhibitory NK receptors, respectively. Allelic variants of the FCGR3A gene include the high-affinity single-nucleotide polymorphism (SNP) rs396991 (V176F), which is associated with the efficacy of monoclonal antibody (mAb) therapies, and the SNP rs10127939 (L66H/R). The contribution of FCGR3A SNPs to NK cell effector functions remains controversial; therefore, the authors generated a panel of eight NK-92 cell lines expressing specific combinations of these SNPs and tested their cytotoxicities. NK-92 cells were stably transfected with plasmids containing different combinations of FCGR3A SNPs. Messenger RNA and FcγRIIIa/CD16 cell surface expressions were detected using new generation sequencing (NGS) and flow cytometry, respectively. All FcγRIIIa/CD16-transfected NK-92 cell lines exhibited robust ADCC against three different target cell lines with minor differences. In addition, enhanced direct NK cytotoxicity against K562 target cells was observed, suggesting a mechanistic role of FcγRIIIa/CD16 in direct NK cytotoxicity. In conclusion, they generated eight FcγRIIIa/CD16-transfected NK-92 cell lines carrying different combinations of two of the most studied FCGR3A SNPs, representing the major genotypes described in the European population. The functional characterization of these cell lines revealed differences in ADCC and direct NK cytotoxicity that may have implications for the design of adoptive cancer immunotherapies using NK cells and tumor antigen-directed mAbs.

Funding: This research was funded by a Private Foundation and the Swiss National Science Foundation, SNSF

Citation: Freitas Monteiro, M.; Papaserafeim, M.; Andreani, M.; Réal, A.; Kouklas, A.; Reis Galvão, D.; Seebach, J.D.; Puga Yung, G.L. NK Cytotoxicity Mediated by NK-92 Cell Lines Expressing Combinations of Two Allelic Variants for FCGR3. Antibodies 2024, 13, 55. https://doi.org/10.3390/antib13030055

WHY IS IT IMPORTANT?

Natural killer (NK) cells are vital for fighting viral infections and the killing of malignant cells. One way of doing this is by sensing antibody-coated target cells through the receptor FcγRIIIa/CD16 another by directly scanning abnormal cells using other receptors. Researchers developed eight unique NK-92 cell lines with different genetic versions of FcγRIIIa/CD16 to see how these variations could influence autoimmune and cancer therapy using antibodies. Therapeutical antibodies are used to target unwanted cells and let the NK cells kill them. By introducing two common genetic changes into these cells, they discovered that certain combinations boost the cells' ability to destroy cancer cells directly or with antibodies. This discovery enhances our understanding of NK killing and may lead to improved therapies using engineered NK cells.

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