ABSTRACT
<p><b>Background </b>: Shigyakusan, a 4-component Japanese herbal medicine (Paeoniae radix, Aurantii fructus immaturus, Glycyrrhizae radix and Bupleuri radix), is used not only for cholecystitis and gastritis as an antiinflammatory agent, but also for anxiety neurosis and insomnia as an anti-anxiety agent.<br><b>Methods </b>: We investigated the effects of shigyakusan on alloimmune responses in fully MHC-mismatched murine cardiac allograft transplantation. CBA mice underwent transplantation of a C57BL/6 heart and received shigyakusan or one component of shigyakusan administered orally from the day of transplantation until 7 days afterward. Histologic studies, cytokine measurements, and flow cytometry assessments were performed.<br><b>Results </b>: Untreated CBA recipients acutely rejected C57BL/6 cardiac grafts (median survival times [MST], 7 days). On the other hand, CBA transplant recipients given shigyakusan had significantly prolonged C57BL/6 allograft survival (MST, 22.5 days). MSTs for C57BL/6 transplant recipients given Paeoniae radix, Aurantii fructus immaturus, Glycyrrhizae radix and Bupleuri radix were 11, 9.5, 18.5 and 8 days, respectively. Additionally, flow cytometry studies showed that the percentage of CD25+Foxp3+ cell populations in CD4+ cells was increased in transplant recipients given shigyakusan.<br><b>Conclusion </b>: Shigyakusan induced hyporesponsiveness to fully MHC-mismatched allogeneic cardiac allografts and may generate CD4+CD25+Foxp3+ cells in our model.</p>