Regulation of cell proliferation, inflammatory cytokine production and calcium mobilization in primary human T lymphocytes by emodin from Polygonum hypoleucum Ohwi

This study was designed to elucidate action mechanisms of four anthraquinones identified from Polygonum hypoleucum Ohwi (P. hypoleucum Ohwi) on primary human T lymphocytes. The cells were isolated from peripheral blood. T cells were treated with 5 to 60 microM of four anthraquinones with or without phytohemagglutinin (PHA; 5 microg/ml) for 3 days. Effects of 4 anthraquinones on T lymphocyte proliferation, production and gene expression of inflammatory cytokines and intracellular free Ca2+ concentration ([Ca2+]i) were determined. Data were assessed with Student's t-test. On a percentage basis, emodin had the highest suppressing activity on T lymphocyte proliferation with an IC50 of 11.2 +/- 0.6 microM. Emodin decreased cytokine production, IL-2 mRNA expression, and [Ca2+]i in activated T cells. We hypothesize that the inhibitory mechanisms of emodin on activated T cells proliferation are related to the impairment of cytokine production, IL-2 mRNA level and [Ca2+]i in the cells.