ABSTRACT
OBJECTIVE: To investigate the active substances with immunoenhancement effect in Prepared Radix Rehmanniae and its mechanism of action. METHODS: Balb/c mice lymphocytes were isolated from thymus and spleens with conventional methods. MTT assay was carried out for proliferation detection, and then ELISA assay was used to measure the levels of Th1 cytokines IL-2, IFN-γ and Th2 cytokines IL-4, IL-5 of lymphocytes from thymus and spleens of the mice. RESULTS: The water extract (0.049, 0.49 and 4. 9 mg · mL-1) and crude polysaccharide extract (0.032, 0.32 and 3.2 mg · mL-1) of Prepared Radix Rehmanniae resulted in strong promotion of thymus and spleen lymphocytes proliferation and obvious increase of IL-2, IFN-γ, IL-4 and IL-5 levels with or without Con A stimulation. These effects were dose-related. CONCLUSION: Prepared Radix Rehmanniae can significantly enhance immune responses, and the active substance might be crude polysaccharide. The mechanism of their immunoenhancement effects is partly due to enhancement of gene expression of Th1/Th2 cytokines of T cells.