Effects of an immunosuppressive active component of Periplocae Cortex (Periploca sepium Bge.) on positive selection of thymocytes in vitro

Abstract

Objective: To determine the effect of an immunosuppressive active component (periploside A) isolated from the stem bark of Periplocae Cortex (Periploca sepium Bge.), a Chinese medicinal herb used in the treatment of rheumatoid arthritis for centuries in China, on positive selection of thymocytes in vitro. Methods: Female C57BL/6 mice at 6 weeks of age were housed in specific pathogen-free conditions. Double-positive thymocytes from C57BL/6 mice were induced into positive selection in vitro with or without periploside A treatment. Cell viability and expression of CD69, CD4, and CD8 were analyzed by flow cytometry. Results: Flow cytometric examination of thymocyte populations revealed that the percentage of CD8+ single-positive thymocytes was decreased by periploside A upon differentiation induced by an anti-CD3 antibody. However, the percentage of CD4+ single-positive thymocytes was decreased by periploside A upon differentiation induced by phorbol 12-myristate 13-acetate/ionomycin. Expression of CD69 plays a major role in prohibiting differentiation of thymocytes. Treatment with periploside A decreased CD69 expression in thymocytes. Conclusion: These results demonstrate that periploside A influences positive selection of thymocytes in vitro. Keywords: Immunosuppressive active component, Positive selection, Thymocytes