Photohardening of polymorphic light eruption patients decreases baseline epidermal Langerhans cell density while increasing mast cell numbers in the papillary dermis

• Published in: Experimental dermatology Vol. 23; no. 6; pp. 428 - 430
• Main Authors: Wolf, Peter, Gruber-Wackernagel, Alexandra, Bambach, Isabella, Schmidbauer, Ulrike, Mayer, Gerlinde, Absenger, Markus, Fröhlich, Eleonore, Byrne, Scott N.
• Format: Journal Article
• Language: English
• Published: Denmark Blackwell Publishing Ltd 01.06.2014
• Subjects: Adult; Biopsy; Case-Control Studies; Cell Count; cytokines; Dermis - pathology; Dermis - radiation effects; Female; Humans; immune suppression; Langerhans Cells - pathology; Langerhans Cells - radiation effects; mast cells; Mast Cells - pathology; Mast Cells - radiation effects; Middle Aged; Photosensitivity Disorders - pathology; Photosensitivity Disorders - therapy; Phototherapy; polymorphic light eruption; PUVA Therapy; Skin Diseases, Genetic - pathology; Skin Diseases, Genetic - therapy; T-Lymphocytes, Regulatory - pathology; T-Lymphocytes, Regulatory - radiation effects; Treatment Outcome; Ultraviolet Rays; cytokines; phototherapy; immune suppression; mast cells; polymorphic light eruption
• ISSN: 0906-6705; 1600-0625
• DOI: 10.1111/exd.12427

The pathogenesis of polymorphic light eruption (PLE) has been linked to a lack of UV‐induced immune suppression. To determine the role of Langerhans cells (LC), mast cells and regulatory T cells, biopsies from PLE patients were taken from exposed sites in spring before and after photohardening with 311 nm or PUVA as well as again in summer. Skin sections were assessed for the presence of Langerin/CD1a+ LC and CD3+, CD4+, CD25+ or FoxP3+ T cells and mast cells. Photohardening transiently decreased the density of epidermal LC and significantly increased a low baseline mast cell density in the papillary dermis of PLE patients. Baseline T cell numbers in the skin were low, and there was no difference in PLE patients among any time point. This suggests that LC suppression together with recruitment of mast cells into photohardened skin may be a key cellular event underlying the mechanism by which phototherapy protects from PLE.