Abstract: OBJECTIVE:To investigate the effects of icariin on apoptosis and the expression of Fas, Fas ligand(Fas L), B cell lymphoma(Bcl-2), and Bcl-2-associated X protein(Bax) in CD4+ T lymphocytes from patients with ankylosing spondylitis.METHODS:Primary cultures of peripheral blood CD4+ T lymphocytes were established and treated with icariin at high, medium, and low doses(0.5,0.25, and 0.125 mg/mL).Sulfasalazine treated and helthy cells were used as controls.Apoptosis of treated cells was determined by flow cytometry.Reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assays were used to determine the effects of icariin on the expression of Fas, Fas L, Bcl-2, and Bax.The activity of caspase 8 and caspase 3 was determined by a colorimetric assay.RESULTS:The m RNA and protein expression of Fas,and activity of caspase 8 and caspase 3 in CD4+ T lymphocytes were increased by icariin(P < 0.05).Conversely, the m RNA and protein expression of Bcl-2 was decreased(P < 0.05).The expression of Fas L and Bax were not significantly different between groups.The proapoptotic effects of icariin were dose-dependent.CONCLUSION:Icariin induces the apoptosis of CD4 + T cells from patients with AS comparing to normal control.Therefore, the induction of apoptosis may be the likely mechanism of action of icariin's antirheumatics activities.

Key words: Spondylitis, ankylosing, Fas, Fas Ligand protein, Lymphoma, B-Cell, Bcl-2-associated X protein, CD4-positive T-lymphocytes, Apoptosis, Icariin