Application of laser fluorescence spectroscopy in non-invasive assessment of ultraviolet-induced skin immune response in vivo

Acute ultraviolet (UV) -induced skin damage is associated with structural alterations, vasodilatation and inflammatory response. Leukocyte infiltration is one of the main features of inflammation and could be found in the area of UV injury. It was shown that porphyrins which have well-known autofluorescent properties play a role in the chemoattraction of immune cells to the area of local damage. This study examined the possibility of application of laser fluorescence spectroscopy (LFS) in the assessment of ultraviolet-induced immune response in ICR mice. Animals (N=25) were exposed by UVB light and LFS was conducted on the dorsal skin of each mice 0, 0.5, 3, 6 and 24 hours after UV irradiation. Moreover, in every time point we performed skin biopsy and histology. Using LFS, time-dependent dynamic changes in the fluorescence parameters of porphyrins were found. Mentioned indices were in a good agreement with histological findings. Statistically significant correlation was found between the severity of inflammatory infiltrate and the tissue content index (η) of porphyrins (Pearson correlation coefficient: r = 0.912, p = 0.031). Achieved results not only have fundamental value but could be further investigated and applied in clinical practice: e.g. to objectively predict individual immunologic reaction to UV-light. © Published under licence by IOP Publishing Ltd.