Interleukin-18 activates NF-kappaB in murine T helper type 1 cells

Interleukin-18 (IL-18) activated T helper type 1 (Th1) cells, OVA#4, and induced production of interleukin-2 (IL-2) in costimulation with anti-CD3 antibody. Upon stimulation with IL-18, IkappaB disappeared from cytoplasm and subsequently nuclear factor-kappaB (NF-kappaB) (p65) accumulated in the nucleus. Corresponding with that, DNA binding activity of NF-kappaB (p65 homodimer or p65/p50 heterodimer) was detected in the nucleus. In the transfection experiments, an IL-2 promoter-driven reporter construct showed the similar responsiveness against IL-18 to that of the intrinsic IL-2 gene, and a construct lacking kappaB site failed to respond to IL-18. These results suggest that IL-18 activates NF-kappaB and it is important for enhancement of IL-2 gene expression by Th1 cells stimulated with IL-18.