Abstract: Objective To investigate the effects of narrow band UVB(NB-UVB)and monochromatic excimer laser 308 nm(MEL 308 nm)on the expression of SCFlkit in keratinocytes and the migration of melanocytes. Methods HaCaT cells were irradiated with 311 nm NB-UVB and MEL 308 nm at various doses(100, 200, and 400 mJ/cm²).Cell culture supernatants(conditioned medium)were harvested at 24 h post-irradiation, and analyzed by enzyme-linked immunosorbent assay(ELISA)for concentration of the c-kit ligand, stem cell factor(SCF)The conditioned medium was examined for its ability to affect the expression of c-kit mRNA in A375 melanoma cells by reverse transcriptase-polymerase chain reaction(RT-PCR),and the migration of A375 cells through the micropore filter. Results In both NB-UVB and MEL 308 nm groups, the concentrations of SCF in UVB-irradiated HaCaT conditioned medium were increasing in a UVB-dose dependent manner. The conditioned medium could significantly induce the expression of c-kit mRNA in A375 cells and significantly enhance the migration of A375 cells(P<0.01).Nevertheless, there was no significant difference in the ability of conditioned medium to induce c-kit expression and enhance the melanocytes migration between the same dose of NB-UVB and MEL 308 nm. Conclusions The results indicate that both NB-UVB and MEL 308 nm can upregulate the expression of SCF in keratinocytes, the expression of kit in melanocytes, and the migration of melanocytes. These may partially account for the therapeutic mechanisms of NB-UVB and MEL 308 nm on vitiligo.

Key words: Keratinocytes, Ultraviolet ray, Stem cell factor