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

Objective and Design: This study was designed to elucidate action mechanisms of four anthraquinones identified from Polygonum hypoleucum Ohwi (P. hypoleucum Ohwi) on primary human T lymphocytes. Material and methods. The cells were isolated from peripheral blood. Treatment: T cells were treated with 5 to 60 muM of four anthraquinones with or without phytohemagglutinin (PHA; 5 mug/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. Results: On a percentage basis, emodin had the highest suppressing activity on T lymphocyte proliferation with an IC50 of 11.2 +/- 0.6 muM. Emodin decreased cytokine production, IL,-2 mRNA expression, and [Ca2+](i) in activated T cells. Conclusions: 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.