Immunomodulatory activity of xanthohumol: inhibition of T cell proliferation, cell-mediated cytotoxicity and Th1 cytokine production through suppression of NF-kappaB.

Xanthohumol (XN), a prenylated chalcone present in hops (Humulus lupus L.) and beer, exhibits anti-inflammatory, antioxidant and antiproliferative activity, but has not been studied for effects on T cell-mediated immune responses. Here we demonstrate that XN has profound immunosuppressive effects on T cell proliferation, development of IL-2 activated killer (LAK) cells, cytotoxic T lymphocytes (CTLs), and production of Th1 cytokines (IL-2, IFN-gamma and TNF-alpha). The suppression of these cell-mediated immune responses by XN was at, least in part, due to the inhibition of nuclear factor kappa B (NF-kappaB) transcription factor through suppression of phosphorylation of IkappaBalpha, an inhibitor of NF-kappaB.