Stine Simonsen, Charlotte M. Bonefeld, Jacob P. Thyssen, Carsten Geisler, Lone Skov
DOI: 10.2340/00015555-3050

This study investigated serum 25-hydroxyvitamin D (25(OH)D) concentrations and circulating regulatory T cells in patients with atopic dermatitis receiving narrow-band ultraviolet B (nbUVB) phototherapy. Thirty adult patients with atopic dermatitis were included. Blood samples were collected at baseline and at weeks 2 and 4 of nbUVB phototherapy. Skin biopsies were taken at baseline and at week 4. Serum 25(OH)D concentrations increased significantly following nbUVB phototherapy (estimate of change from baseline to week 2: 32.00 nmol/l, confidence interval (CI) 20.48–43.52, p < 0.0001, n = 25; and from baseline to week 4: 50.30 nmol/l, CI 37.28–63.33, p < 0.0001, n = 18). This increase was independent of the filaggrin gene FLG loss-of-function mutation status. Flow cytometry showed no significant change in regulatory T cells or cytokine profiles of T cells in blood. Real-time quantitative PCR showed no change in skin cytokine levels. In conclusion, nbUVB phototherapy was associated with increased serum 25(OH)D concentrations, but not changes in circulating regulatory T cells in patients with atopic dermatitis.

Vitamin D synthesis is induced by ultraviolet B irradiation of the skin and may have a beneficial effect on the immune system in patients with atopic dermatitis. We measured changes in vitamin D levels and immunological markers in patients with atopic dermatitis receiving ultraviolet B photo­therapy. Following ultraviolet B phototherapy, vitamin D levels were increased, as expected, but no changes were found in the immune system. Furthermore, ultraviolet B phototherapy induced equal increases in the vitamin D levels in patients with atopic dermatitis with and without a mutation that causes a defective skin barrier.

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