Selective Th1 up-regulating activity of Withania somnifera aqueous extract in an experimental system using flow...

Withania somnifera (Ashwagandha) is reported to be immunoprotective and immunoadjuvant. We studied its roots aqueous extract on T helper (Th) immunity using flow cytometry. This extract was standardized with six withanolides as marker compounds using HPLC. Once daily dose ranging from 25 to 400 mg/kg/p.o. was used to study effect on Th1: IFN-gamma, IL-2 and Th2: IL-4 cytokine modulation. We also studied effect on CD4 and CD8 in normal and immunesuppressed mice. The results indicate that extract at 100 mg/kg resulted significant selective up-regulation of Th1 response. Treatment with extract showed significant increase in CD4 and CD8 counts as compared to control and cyclopsorin A, with a faster recovery of CD4+ T cells in immunesuppressed animals. Under immunesuppressed conditions, potentiation of cellular and humoral immune responses of extract was comparable to levamisole. This study indicates the selective Th1 up-regulating effect of extract and suggests its use for selective Th1/Th2 modulation.