Gene-modified NK Cells Expressing CD64 and Pre-loaded with HIV-specific BNAbs Target Autologous HIV-1 Infected CD4+ T Cells by ADCC.
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 pre-load them with HIV-specific 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 (PLWH) were activated with 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 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 week antibody retention assay) compared to Control NK cells only expressing CD16. BNAb pre-loaded 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 3 hour degranulation assay as well as a 24 hour HIV p24 HIV Elimination Assay when compared to control NK cells. A chimeric CD64 enhanced NK cell strategy (NK Enhancement Strategy, "NuKES") retaining bound HIV-specific antibody and targeted ADCC represents a novel autologous primary NK cell immuno-therapy strategy against HIV.