Arctigenin from Arctium lappa inhibits interleukin-2 and interferon gene expression in primary human T lymphocytes

Cell proliferation was determined with enzyme immunoassays and the tritiated thymidine uptake method. Cytokine production and gene expression were analyzed with reverse transcription-polymerase chain reaction.AC inhibited primary human T lymphocytes proliferation activated by anti-CD3/CD28 Ab. Cell viability test indicated that the inhibitory effects of AC on primary human T lymphocyte proliferation were not due to direct cytotoxicity. AC suppressed interleukin-2 (IL-2) and interferon-γ (IFN-γ) production in a concentration-dependent manner. Furthermore, AC decreased the IL-2 and IFN-γ gene expression in primary human T lymphocytes induced by anti-CD3/CD28 Ab. Reporter gene analyses revealed that AC decreased NF-AT-mediated reporter gene expression.AC inhibited T lymphocyte proliferation and decreased the gene expression of IL-2, IFN-γ and NF-AT.The central event in the generation of immune responses is the activation and clonal expansion of T cells. Interaction of T cells with antigens initiates a cascade of biochemical events and gene expression that induces the resting T cells to activate and proliferate [1]. Activation of nuclear factor of activated T cells (NF-AT) and a series of genes such as interleukin-2 (IL-2) and interferon-γ (IFN-γ) are pivotal in the growth of T lymphocytes induced by antigens [2,3]. Thus, growth modulators or other external events affecting T cell proliferation are likely to act by controlling the expression or function of the products of these genes [4]. The immune responses to invasive organisms, if inappropriately intense or prolonged, may paradoxically aggravate the injury or even cause death. The use of immunomodulatory medications must therefore be discreet. Regulation of T lymphocyte activation and proliferation and cytokine production is one of the action mechanisms [5,6].Chinese medicinal herbs are now widely acknowledged for their immunomodulatory activities [1]. A member of the Compositae family, Arctium lappa (Niubang) is re