The effect of narrowband ultraviolet B on tissue level of interleukin-15 and interleukin-15 receptor alpha subunit in active nonsegmental vitiligo cases: an interventional cohort study

BackgroundVitiligo is an acquired depigmenting skin disorder in which CD8 effector and memory T-cells contribute to its pathogenesis and recurrence. Interleukin (IL)-15 contributes to CD8 effector T-cell cytotoxicity and CD8 memory T-cell survival and maturation.ObjectiveTo evaluate the effect of total narrowband ultraviolet B (NB-UVB) on tissue levels of IL-15 and IL-15 receptor alpha (IL-15Ra) in active nonsegmental vitiligo.Patients and methodsThe patients were assessed clinically for vitiligo extent and activity before and after treatment. Perilesional skin biopsies were taken from 30 vitiligo patients before and after 48 sessions of NB-UVB and from 30 healthy controls. Tissue levels of IL-15 and IL-15 Ra were evaluated by enzyme-linked immunosorbent assay before and after treatment to evaluate the effect of NB-UVB on them.ResultsBefore NB-UVB treatment, the tissue levels of both IL-15 and IL-15Ra were significantly higher in vitiligo patients than controls; moreover, they were significantly higher than those after NB-UVB treatment. In contrast, after NB-UVB treatment, no statistically significant difference was detected between the patients and controls. The levels of IL-15 and IL-15Ra were significantly correlated, whereas they were not correlated with either vitiligo activity or extent.ConclusionIL-15 and IL-15Ra were higher in vitiligo patients than controls before treatment. However, their tissue levels were normalized after treatment with NB-UVB, emphasizing its therapeutic potential.