Silymarin suppress CD4+ T cell activation and proliferation: Effects on NF-κB activity and IL-2 production

Silymarin, a mixture of bioactive flavonolignans isolated from Silybum marianum, exhibits anti-carcinogenic, anti-inflammatory and cytoprotective effects. In this study, the in vitro immunomodulatory activity of silymarin was investigated using CD4+ splenocytes from C57/Bl6 mice. Proliferation assay revealed that silymarin, at 50 μM concentration, significantly inhibited CD4+ cells proliferation. ELISA analyses indicated that silymarin significantly inhibited IL-2 and IFN-γ production. Immunofluorescence staining performed on the mouse hybridoma T cell line (3DO) revealed a block of nuclear translocation of transcription factor κB (NF-κB), which is known to be responsible for IL-2 transcriptional activation. Moreover, silymarin inhibited p65/NF-κB phosphorylation in CD4+ T cell. These results suggest that silymarin is able to inhibit T cell activation and proliferation, notably acting on pathways of NF-κB activation/translocation.