Short-term hypoxia synergizes with interleukin 15 priming in driving glycolytic gene transcription and supports human natural killer cell activities.

Natural killer (NK) cells induce apoptosis in infected and transformed cells and produce immunoregulatory cytokines. At this, NK cells operate in inflammatory and tumor environments low in oxygen (hypoxic) and with immunosuppressive properties. In vitro studies of NK cells are, however, commonly performed in ambient air (normoxia). We evaluated the immediate impact of short-term hypoxia on various intrinsic activities of resting and IL-15 primed NK cells and determined underlying transcriptional pathway regulations using a 2 × 2 factorial design. Hypoxia stimulated migration through extracellular matrix, supported secretion of specific chemokines, and shifted amounts of susceptible leukemia target cells toward late apoptosis. IL-15 was a powerful inducer of anabolic gene transcription. Associations of hypoxia with HIF-1 and glycolytic pathways were dependent on priming which represented the largest contrasts observed. Regulatory patterns and RT-PCR validated synergistic hypoxia-IL-15 interactions in upregulation of key glycolytic enzymes suggest an important function for anaerobic glycolysis in priming, underpinning the emerging role of glycolytic switching in driving NK cell function. Adaption to short-term hypoxia appeared however transitory. We conclude that control of oxygen in vitro can promote NK cell features desirable for adoptive transfer therapy. In five independent experiments, NK cells from healthy donors were enriched by immunomagnetic labeling and separation (negative selection, yielding >95% CD56+CD3-) and cultured in parallel under normoxia or hypoxia with or without IL-15 priming toward the end of the incubation.