Engineering lymph node homing of ex vivo-expanded human natural killer cells via trogocytosis of the chemokine receptor CCR7.

Natural killer (NK) cells have gained significant attention in adoptive immunotherapy for cancer. Consequently, novel methods of clinical-grade expansion of NK cells have emerged. Subsets of NK cells express a variety of chemokine receptors. However, to expand the scope of adoptively transferred NK cell homing to various malignancies, expression of corresponding chemokine receptors on NK cells is essential. Here, we have explored the use of trogocytosis as a tool to transiently express the chemokine receptor CCR7 on expanded human NK cells with the aim to enhance their homing to lymph nodes. We generated a K562-based "donor" cell line expressing CCR7, Clone9.CCR7, to transfer CCR7 onto NK cells via trogocytosis. CCR7 expression occurred in 80% of expanded NK cells within 1 hour after coculture with Clone9.CCR7. After removal of the donor cells from the coculture, the CCR7 expression on NK cells steadily declined to baseline levels by 72 hours. The acquired CCR7 receptors mediated in vitro migration of NK cells toward CCL19 and CCL21 and increased the lymph node homing by 144% in athymic nude mice. This is the first report on exploiting trogocytosis to rapidly and transiently modify lymphocytes, without direct genetic intervention, for adoptive transfer.