Background Antibody-dependent cell-mediated cytotoxicity (ADCC) is an important mechanism by which natural killer (NK) cells neutralize infected cells through antibodies. This process is mediated by CD16A, an Fc receptor (FcR) encoded by the gene FcγRIIIA which binds to IgG and activates NK cells to attack target cells. CD16A is expressed in human NK cells, but not in mouse NK cells due to the lack of the homologous gene FcγRIV. As a result, it can be challenging to accurately evaluate the effectiveness of human NK-dependent ADCC using mouse NK cells.

Methods Here we present new strategies for the reconstitution of humanized NK cells through NCG-hIL2 or NCG-hIL15 mice transplanted with CD34+ hematopoietic stem cells (HSC), greatly facilitating preclinical evaluation of the ADCC activity of antibodies.

Results Theses NK cells express NKp30, NKp46, NKG2D, CD94, and various Ig-like receptor molecules of killer cells, and produce amounts of granzyme B. There is evidence that the humanized NK cells can exhibit ADCC activity against tumor cells in vitro. Furthermore, when administered to huHSC-NCG-hIL2 mice engrafted with Trastuzumab-resistant JIMT-1 tumor cells at equivalent doses, the anti-HER2 antibody Margituximab (which has a higher affinity for CD16A) demonstrated superior anti-tumor effects than its structurally similar counterpart, Trastuzumab.

Conclusions In summary, the successful reconstruction of functional human NK cells in humanized mouse models provides a useful tool to preclinically evaluate the ADCC activity of therapeutic antibodies, potentially predicting their clinical efficacy.