Protein-bound polysaccharide K and interleukin-2 regulate different nuclear transcription factors in the NKL human natural killer cell line

The activation of natural killer cells and induction of cytotoxicity are co mplex processes whose molecular mechanisms have not been clearly elucidated . Stimulation of the NKL human NK cell line with interleukin-2 (IL-2) or pr otein-bound polysaccharide K (PSK) leads to sustained growth and cytolytic activity in comparison to unstimulated NKL cells. However, it is not known whether both agents give rise to the same or different intracellular signal s. To determine the molecular basis for the action of IL-2 and PSK, the bin ding activity of AP-1, CRE, NF-kappaB, PU.1, SP-1, NFAT, STAT1, STAT5/6, GA S/ISRE and IRF-1 transcription factors was compared in IL-2- and PSK-stimul ated NKL cells. Here we report that PSK enhanced AP-1 and CRE binding activ ities, whereas IL-2 increased AP-1 and SP-1 and modified GAS/ISRE, IRF-1 an d STAT5. Our results indicate that IL-2 and PSK regulate different nuclear transcription factors in NKL cells, and that the signal transduction pathwa y used by these inducers is different.