Ex vivo activation and expansion of natural killer cells from patients with advanced cancer with feeder cells from healthy volunteers

Background aims. Culturing natural killer (NK) cells from patients with advanced cancer is difficult and has restricted the generation of sufficient cell numbers for autologous adoptive NK-cell therapy. The aim of this study was to establish a novel method for ex vivo NK-cell expansion from patients with cancer. Methods. NK cells (CD3(-)CD56(+)) were isolated from peripheral blood mononuclear cells from healthy volunteers and cancer patients, and NK- fractions were used as feeder cells. Purified NK cells were co-cultured with feeder cells in AIM-V medium (Invitrogen, Carlsbad, CA, USA) supplemented with 5% human serum and 1000 units/mL human interleukin-2. Results. NK cells co-cultured with feeder cells from healthy volunteers (feeder-HV) expanded more than NK cells co-cultured with feeder cells from cancer patients (feeder-CP). During the 14-day culture period, NK cells from patients with advanced cancer co-cultivated with feeder-HV expanded on average 300-fold. NK cells co-cultivated with feeder-CP expanded on average 169.4-fold. Cultures grown in the presence of feeder-HV contained 93.8 +/- 7.0% (mean +/- standard deviation; n = 6) CD3(-)CD56(+) NK cells, and cultures grown in the presence of feeder-CP contained 83.6 +/- 15.9% CD3(-)CD56(+) NK cells. Feeder-HV caused a relative increase in CD3(+)CD4(+) T cells, whereas feeder-CP did not induce changes. Interleukin-15, a cytokine that induces NK-cell proliferation, was detected in the culture supernatants of feeder-HV but not in those of feeder-CP. Conclusions. Feeder cells obtained from healthy volunteers have the potential to expand and activate NK cells from patients with advanced cancer. The novel NK-cell expansion method described here provides a technique for acquiring the large numbers of highly active NK cells from patients with cancer for autologous adoptive immunotherapy.