Density of Langerhans cells in chronic plaque psoriatic lesions before and after phototherapy

Introduction: Langerhans cells (LCs) constitute a key component of the skin immune system (SIS). They play some role in the pathogenesis of chronic inflammatory diseases of the skin, including psoriasis. However, their role in psoriasis has not been completely elucidated. The aim of this study was to evaluate LCs density in skin lesions of patients with chronic plaque psoriasis, before and after phototherapy. Material and methods: 25 patients with plaque psoriasis were included in the study. Biopsies were taken from the skin of their lumbosacral or gluteal area. Then the participants received broadband UVB, narrowband UVB or PUVA therapy. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded skin samples using antihuman CD1a antibody (NCL-CD1a-235, Novocastra). Results: The number of LCs in the study group was lower in lesional skin compared to perilesional skin. After phototherapy we observed an increase in the number of LCs in lesional skin while a decrease of the LCs number was noted in perilesional skin after PUVA treatment. Conclusions: Psoriatic epidermis is characterized by disturbances in the number of LCs. Our study showed a low number of LCs in chronic psoriatic plaques. At the same time, a high number of LCs in perilesional skin may predict centrifugal enlargement of psoriatic plaques. However, a smaller number of LCs may be observed in chronic lesions. The most considerable increase of LCs number was observed in psoriatic skin of our patients after BB-UVB and PUVA treatment, a slight increase -after NB-UVB therapy.