Description
Natural Killer cells (NK), a major constituent of innate immune system, have the ability to kill the transformed and infected cells without prior sensitization; can be put to immunotherapeutic use against various malignancies. NK cells discriminate between normal cells and transformed cells via a balance of inhibitory and activating signals induced by interactions between NK cell receptors and target cell ligands. Present study investigates whether expansion of NK cells could augment their anti-myeloma (MM) activity. For NK cell expansion, peripheral blood mononuclear cells from healthy donors and myeloma patients were co-cultured with irradiated K562 cells transfected with 4-1BBL and membrane-bound IL15 (K562-mb15-41BBL). A genome-wide profiling approach was performed to identify gene expression signature in expanded NK (ENK) cells and non-expanded NK cells isolated from healthy donors and myeloma patients. A specific set of genes involved in proliferation, migration, adhesion, cytotoxicity, and activation were up regulated post expansion, also confirmed by flow cytometry. Exp-NK cells killed both allogeneic and autologous primary MM cells more avidly than non-exp-NK cells in vitro. Multiple receptors, particularly NKG2D, natural cytotoxicity receptors, and DNAM-1 contributed to target lysis, via a perforin mediated mechanism. In summary, vigorous expansion and high anti-MM activity both in vitro and in vivo provide the rationale for testing exp-NK cells in a clinical trial for high risk MM.