Immunomodulatory effects of silymarin in patients with β-thalassemia major.

OBJECTIVE: Silymarin, a flavonolignan complex isolated from milk thistle, is a cytoprotective, antioxidant, and hepatoprotective agent. The present study was designed to investigate the immunomodulatory effects of orally administered silymarin in patients with β-thalassemia major.

METHODS: The immunomodulatory effects of silymarin were investigated in a 12-week clinical trial in two groups of patients. In combined therapy group (n=25), patients continued desferrioxamine at the dose of 40mg/kg/day and Legalon® tablets (420mg daily) were added to desferrioxamine. In silymarin group (n=5), patients who were unable or unwilling to use desferrioxamine received only silymarin. Immunological tests were assessed at the beginning and the end of the trial.

RESULTS: No differences were detected between treatment groups regarding the percentage of lymphocyte subsets, concentration of serum immunoglobulins, complement levels, or T cell proliferation in vitro. Serum tumor necrosis factor (TNF-α) levels were significantly decreased in both groups, whereas the serum levels of neopterin significantly decreased in both groups after silymarin therapy. The analysis of cell culture supernatants of activated T cells showed increased production of interferon gamma (IFNγ) and interleukin (IL)-4 after silymarin treatment in both groups.

CONCLUSION: Silymarin stimulates cell-mediated immune response in β-thalassemia major, possibly through a direct action on cytokine-producing mononuclear cells. Because of its immunostimulatory, antioxidant, and iron-chelating activities, silymarin could be a good candidate in the therapy of chronic iron overload in combination with routine iron chelators in clinical use like desferrioxamine.