Chimeric Antigen Receptor T Cell Targeting of Natural Killer Cells in Peripheral Blood and Tissues of Rhesus Macaques

Natural killer (NK) cells lead a rapid and potent innate immune response following exposure to infectious agents, but their activity may also contribute to chronic inflammation and augmented disease pathogenesis. Previous reports have shown that Janus kinase 3 inhibitors or anti-IL-15 monoclonal antibodies potently deplete NK cells in nonhuman primates (NHPs). However, they also disrupt T cell homeostasis, making it difficult to use these reagents to delineate the nonredundant role of NK cells in NHPs. To induce the specific depletion of NK cells in vivo, we designed chimeric antigen receptor (CAR) T cells targeting either a broad (CD16⁺) or narrow (NKG2A/C⁺) proportion of NK-inclusive innate immune subsets in rhesus macaques (RM). Ex vivo screening assays identified anti-CD16 and anti-NKG2A/C CAR constructs that potently and specifically depleted CD16⁺ and NKG2A/C⁺ cells, respectively, in the presence of autologous peripheral blood mononuclear cells (PBMCs). Adoptive transfer of autologous anti-NKG2A/C CARs was associated with a profound depletion of NK cells in blood and tissues of RM. NK cell depletion occurred despite modest anti-NKG2A/C CAR T cell expansion and persistence. No target cell depletion was observed following anti-CD16 CAR T-cell infusion, potentially due to the CAR T-cell dose and/or infusion frequency, animal-specific factors, or limitations of the CAR construct. Collectively, our pioneering study expands the application of CAR T cells as a basic science tool and further advances the NHP model for studying NK cell activity in disease contexts, such as infectious diseases and allotransplantation.