Vitamin K₂ immunosuppressive effect on pediatric patients with atopic dermatitis

Over 20 kinds of steroids, tacrolimus ointments, and cyclosporine capsules are usually recommended for the treatment of atopic dermatitis (AD), depending on the symptoms of patients. However, several side effects sometimes occur with the extensive use of these agents for the treatment of pediatric AD patients. The purpose of this study was to explore whether vitamin K₂ could be a new immunosuppressive candidate for pediatric patients with AD.

The immunosuppressive efficacy of vitamin K₂ was evaluated through a cell-culture procedure using mitogen-activated peripheral blood mononuclear cells (PBMCs) obtained from pediatric AD patients.

The mean (SD) IC₅₀ value of vitamin K₂ for the proliferation of concanavalin A-activated PBMCs was 15.37 (30.05) μmol/L, while the value for tacrolimus was 0.10 (0.28) ng/mL (0.12 (0.35) nmol/L). There was a significant correlation between the IC₅₀ values for vitamin K₂ and those for tacrolimus (P = 0.0001, r = 0.8871). However, there was no significant correlation between the IC₅₀ values of vitamin K₂ and those of cyclosporine A or methylprednisolone. A significant correlation between the IC₅₀ values of vitamin K₂ or tacrolimus and blood eosinophil counts (P = 0.0099, r = 0.7086 and P = 0.0032, r = 0.7722, respectively) was observed.

Vitamin K₂ -inhibited T-cell mitogen stimulated proliferation of PBMCs from pediatric AD patients in a dose-dependent manner. The PBMCs from pediatric AD patients were more sensitive to the immunosuppressive efficacy of vitamin K₂ than the PBMCs from healthy subjects. The individual immunosuppressive pharmacological efficacy of vitamin K₂ and of tacrolimus could be inferred from the blood eosinophil count of pediatric AD patients.