We studied the ability of cytokines to activate the nuclear transcription factor NF-κB in human pancreatic islets and the putative role of NF-κB for cytokine-induced NO production. Brief exposure (20 min) of human islets of Langerhans to a combination of interleukin-lβ + interferon-γ + tumor necrosis factor-a induced a 2.6-fold increase in nuclear NF-κB activity in gel shift analysis. This increase was prevented by the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), which also counteracted NO production by human islets exposed for 14 h to the cytokine combination. High concentrations of interleukin-lβ alone (150 and 250 U/ml) increased NF-κB nuclear binding but failed to induce NO formation in human islets. The present data are the first to demonstrate that cytokines activate NF-κB in primary adult human pancreatic islets and suggest that activation of NF-KB may be a necessary but not sufficient signal for cytokine-induced iNOS expression in human islets of Langerhans.