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Astragali radix, which has tonifying and circulatory effect as well as immune response, is one of the oldest and most frequently used crude drug for oriental medicine in many Asian countries. The present study was conducted to evaluate the effect of aqueous extract of Astragali radix (ARE) on the functions of murine macrophage cell line, RAW 264.7 macrophage cells. In the cell proliferation assay, methotrexate (MTX), an agent of immune suppression, decreased the cell proliferation of RAW 264.7 macrophage cells (IC(50): 100 microg/ml), but the suppression of cell proliferation was significantly protected by ARE treatment in RAW 264.7 macrophage cells. The expressions of cytokine gene by ARE were investigated using reverse transcription polymerase chain reaction (RT-PCR). In RT-PCR, IL-1alpha, IL-1beta and IL-6 mRNA expressions was induced in ARE-treated RAW 264.7 macrophage cells. We also investigated the effect of the nitric oxide (NO) synthesis and inducible nitric oxide synthase (iNOS) mRNA expression by ARE. ARE alone had no effect on NO synthesis and iNOS mRNA expression in RAW 264.7 cells. In the case of lipopolysaccharide (LPS) stimulation, NO production and iNOS mRNA expression were detected in RAW 264.7 cells. However, NO production and iNOS mRNA expression which is induced by LPS decreased after treatment of ARE. These data demonstrate that ARE can reduce the suppression of macrophage cell proliferation induced by MTX, and induce IL-1alpha, IL-1beta and IL-6 mRNA expressions in RAW 264.7 macrophage cells. Also, ARE inhibit NO production in LPS-stimulated RAW 264.7 macrophage cells, and the inhibition of NO production may be associated with the inhibition of iNOS mRNA expression.

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 (IC(50):800 microg/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-1alpha, IL-1beta, IL-12p40, GM-CSF and TNF. Enhancement of IL-1alpha and IL-12p40 mRNA expressions were shown in mouse spleen cells by ARE. In spite of MTX treatment, the expressions of IL-1alpha 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-1alpha and IL-12p40 mRNA as well as the mitogenic effect on spleen cells., (Copyright 2002 Elsevier Science Ireland Ltd.)