Immunomodulatory effects of aqueous-extracted Astragali radix in methotrexate-treated mouse spleen cells

Abstract

The present study was conducted to evaluate the immunomodulatory effect of aqueous-extracted Astragali radix (ARE) in methotrexate (MTX)-treated mouse spleen cells. In spleen cell proliferation assay, ARE enhanced mitogenic activity in the dose–response manner. We also investigated the effect of ARE on the reducing of immune suppression caused by MTX in mouse spleen cells. MTX decreased the spleen cell proliferation (IC50:800 μg/ml). However, ARE significantly reduced the suppression of cell proliferation by MTX in mouse spleen cells. Immunomodulatory effect of ARE were further investigated using reverse transcription polymerase chain reaction (RT-PCR). In RT-PCR, we examined the expressions of various cytokines such as IL-6, IL-1α, IL-1β, IL-12p40, GM-CSF and TNF. Enhancement of IL-1α and IL-12p40 mRNA expressions were shown in mouse spleen cells by ARE. In spite of MTX treatment, the expressions of IL-1α and IL-12p40 mRNA sustained in spleen cells. These data indicate that (1) ARE has a protective effect of immune suppression, and (2) the immunomodulatory effects of ARE may be, in part, associated with the expressions of IL-1α and IL-12p40 mRNA as well as the mitogenic effect on spleen cells.