Production of Th1- and Th2-dependent cytokines induced by the Chinese medicine herb, Rhodiola algida, on human peripheral blood monocytes

Ethnopharmacological relevance
Rhodiola algida, an herb ingredient used in Chinese medicine, has been clinically proven to be effective in enhancing human immune responses.

Aim of study
This study attempted to identify the potential immunomodulatory effect of Rhodiola algida extract in human immune system in vitro, and to examine its underlying molecular effects.

Materials and methods
Firstly, the bioactive marker compound salidroside was used for standardization of Rhodiola algida extract by reversed-phase HPLC. Secondly, the regulation of human immune responses was investigated in human peripheral blood monocytes. A series of cytokines known to play important roles in the human immune responses were examined.

Results
The current study provided quantitative assay for the marker compound, salidroside, in the Rhodiola algida extract for ensuring the quality consistency of Rhodiola algida used in the following experiments. Biological assay indicated that Rhodiola algida stimulates human peripheral blood lymphocytes and its underlying immunomodulatory effects probably through its regulation of IL-2 in Th1 cells and IL-4, IL-6, IL-10 in Th2 cells.

Conclusion
The findings may enable us to further explain the pharmacological properties in Chinese medicine and make Rhodiola algida a very promising immunomodulating agent.