Immuno-enhancing effects of the herbal extract from Himalayan rhubarb Rheum emodi Wall. ex Meissn

In the present studies, the immuno-enhancing activity of Rheum emodi ethyl acetate rhizome extract has been carried out by conducting studies on the cell lines. The studies include effects on signal transduction parameters that could pave the way for understanding some of the treatment principles of the plant extracts. The data indicate that R. emodi may have an immuno-enhancing effect through the release of various cytokines. There is a dose dependent increase in the release of NO (nitric oxide) and cytokine TNF-α, IL-12 and a decrease in IL-10 by RAW 264.7 in macrophage cell lines in the presence of extract alone. However the cytokine level is concomitantly increased in the presence of stimulant as well as extract. The up-regulation of TNF-α, and IL-12 up to the level of 200 ng/ml and 530 ng/ml respectively switches the cell towards Th-1 immune response. TNF-α, IL-12 induces generation and proliferation of Th-1 cells which in turn produces NK and cytotoxic T-cells. On the other hand, the decreased levels of IL-10 switches off the Th-2 immune system and directs the cell towards Th-1 immune response only. Thus, indicating that R. emodi extract may have anti-tumour effects by regulating Th-1 and Th-2 immune response in vivo.