Immunomodulatory effect of vitamin K2: Implications for bone health

OBJECTIVE:In women with postmenopausal osteoporosis, vitamin K2 appears to decrease the incidence of hip, vertebral, and non-vertebral fractures. Women with postmenopausal osteoporosis have more circulating activated T cells compared with healthy postmenopausal and premenopausal women, but the effects of vitamin K2 on T cells have not been studied. In this study, we have looked at T-cell suppression by vitamin K2. MATERIALS AND METHODS:Peripheral blood mononuclear cells (PBMCs) from three healthy donors were used. The PBMCs were stimulated with the mitogens phytohemagglutinin and concanavalin A, and T-cell proliferation was analyzed using flow cytometry based on carboxyfluorescein succinimidyl ester (CSFE) dye dilution. RESULTS:Vitamin K2 (60 and 100 μM) inhibited T-cell proliferation. Vitamin K1 at the same concentrations did not inhibit T-cell proliferation. CONCLUSION:Vitamin K2 has immunomodulatory activities.