Gene-modified NK cells expressing CD64 and preloaded with HIV-specific BNAbs target autologous HIV-1-infected CD4+ T cells by ADCC

Abstract

Natural killer (NK) cells can efficiently mediate antibody-dependent cellular cytotoxicity (ADCC) of antibody coated target cells via the low-affinity Fc-receptor, CD16, but cannot retain antibodies over time. To increase antibody retention and facilitate targeted ADCC, we genetically modified human NK cells with the high-affinity Fc receptor, CD64, so that we could preload them with HIV-specific broadly neutralizing antibodies (BNAbs) and enhance their capacity to target HIV-infected cells via ADCC. Purified NK cells from the peripheral blood of control donors or persons living with HIV were activated with interleukin (IL)-2/IL-15/IL-21 cytokines and transduced with a lentivirus encoding CD64. High levels of CD64 surface expression were maintained for multiple weeks on NK cells and CD64-transduced NK cells were phenotypically similar to control NK cells with strong expression of CD56, CD16, NKG2A, NKp46, CD69, HLA-DR, CD38, and CD57. CD64-transduced NK cells exhibited significantly greater capacity to bind HIV-specific BNAbs in short-term antibody binding assay as well as retain the BNAbs over time (1-wk antibody retention assay) compared with control NK cells only expressing CD16. BNAb-preloaded CD64-transduced NK cells showed a significantly enhanced capacity to mediate ADCC against autologous HIV-1-infected CD4+ primary T cells in both a short-term 4 h degranulation assay as well as a 24 h HIV p24 HIV elimination assay when compared with control NK cells. A chimeric CD64 enhanced NK cell strategy (NuKEs [NK Enhancement Strategy]) retaining bound HIV-specific BNAbs represents a novel autologous primary NK cell immunotherapy strategy against HIV through targeted ADCC.

Keywords: NK cells; antibody-dependent cellular cytotoxicity (ADCC); broadly neutralizing antibodies (BNAb); high-affinity Fc receptor CD64; persons living with HIV.