Ultraviolet irradiations, such as narrow band UVB (NB-UVB) and excimer light, have been frequently employed to reduce pruritus, which is intractable to existing treatments. The aim of this study was to consider difference between NB-UVB and excimer light in the impact on pruritus.
To investigate this question, gene-expression profile in cultured normal human epidermal keratinocyte (NHEK) irradiated with NB-UVB or excimer light was made, and the specific features and characteristics of each irradiation were analyzed in this study. NHEK was irradiated with 50mJ/cm2 of NB-UVB or excimer light. After 6 hours later, mRNAs were harvested, and were analyzed with micro-array study. Subsequently, real-time PCR analyses were performed to evident the distinguishing changes in gene expression. 
In general, difference in metabolic pathway was found between those irradiations. Pronounced change of gene expressions related to pruritus was found in both irradiations. Among them, change in gene expressions of CCR6 ligand, IL-10 family, and ligand of epidermal growth factor receptor was more marked in NHEK irradiated with excimer light.
From these results, irradiation with NB-UVB and excimer light coordinately regulate the gene expression from keratinocyte to maintain the skin homeostasis in distinctive way, and might reduce pruritus.

Comparison of gene expression profiles in keratinocyte irradiated with narrow band UVB and excimer light: implication for the mechanisms of their anti-pruritic effects.