Effects of vitamin K3 and K5 on proliferation, cytokine production, and regulatory T cell-frequency in human peripheral-blood mononuclear cells

AimsThe effects of vitamin K (VK) derivatives VK3 and VK5 on human immune cells have not been extensively investigated. We examined the effects of VK3 and VK5 on proliferation, apoptosis, cytokine production, and CD4+CD25+Foxp3 + regulatory T (Treg) cell-frequency in human peripheral blood mononuclear cells (PBMCs) activated by T cell mitogen in vitro.Main methodsAnti-proliferative effects of VK3 and VK5 on T-cell mitogen activated PBMCs were assessed by WST assay procedures. Apoptotic cells were determined as Annexin V positive/propidium iodide (PI) negative cells. Cytokine concentrations in the supernatant of the culture medium were measured with bead-array procedures followed by analysis with flow cytometry. The CD4+CD25+Foxp3+Treg cells in mitogen-activated PBMCs were stained with fluorescence-labeled specific antibodies followed by flow cytometry.Key findingsVK3 and VK5 suppressed the mitogen-activated proliferation of PBMCs significantly at 10–100 μM (p < 0.05). The data also suggest that VK3 and VK5 promote apoptosis in the mitogen-activated T cells. VK3 and VK5 significantly inhibited the production of tumor necrosis factor (TNF) α, interleukin (IL)-4, -6, and -10 from the activated PBMCs at 10–100 μM (p < 0.05). In contrast, VK3 and VK5 significantly increased Treg cell-frequency in the activated PBMCs at concentrations more than 10 μM (p < 0.001).SignificanceOur data suggest that VK3 and VK5 attenuate T cell mediated immunity by inhibiting the proliferative response and inducing apoptosis in activated T cells.