Effects of topical pimecrolimus 1% on high-dose ultraviolet B-irradiated epidermal Langerhans cells

Abstract

Some studies reported no changes in the number of epidermal Langerhans cells (LC) that were observed in mice treated with pimecrolimus, and low-dose stimulated solar radiation (once)-induced changers in LC are minimally affected by pimecrolimus. This study is to investigate the effects of topical pimecrolimus 1% on high-dose ultraviolet B (UVB)-irradiated epidermal LC. Forty human foreskin tissues were randomly divided into 4 groups of 10 tissues each: Group A, control; Group B, pimecrolimus 1% (once)-only; Group C, 180mJ/cm2 UVB (once)-only; Group D, UVB+pimecrolimus. Each tissue was cut into 4 pieces corresponding to 4 time points. All the tissues were cultured at 37°C. After being treated, the tissues were collected respectively and processed for immunohistochemical staining and immunofluorescence staining. For UVB-only group, epidermal CD1a+ LC number at 18h decreased from 39.6±8.30 to 22.3±2.26/5 high magnification, compared to CD1a+ LC number at 0h (P<0.01). The CD1a+ LC number of UVB-only group was significantly less than other groups at 18h, 24h and 48h (P<0.05, respectively). Similar results were obtained with immunofluorescence staining for CD 1a and immunohistochemical staining for Langerin. The numbers of epidermal HLA-DR+ LC had no significant differences among all groups at different time points. Our study found a single 180mJ/cm2 UVB irradiation significantly reduced epidermal LC numbers at 18h, 24h and 48h, however, topical pimecrolimus could reverse these changes. UVB plus pimecrolimus treatment did not affect human LC maturation.