Differential Expression of Cytokines in UV-B–Exposed Skin of Patients With Polymorphous Light Eruption: Correlation With Langerhans Cell Migration and Immunosuppression

BACKGROUND Disturbances in UV-induced Langerhans cell migration and T helper (TH) 2 cell responses could be early steps in the pathogenesis of PLE. OBJECTIVE To establish whether UV-B exposure induces aberrant cytokine expression in the uninvolved skin of patients with polymorphous light eruption (PLE). DESIGN Immunohistochemical staining and comparison of microscopic sections of skin irradiated with 6 times the minimal dose of UV-B causing erythemaand the unirradiated skin of patients with PLE and of healthy individuals. SETTING University Medical Center (Dutch National Center for Photodermatoses). PATIENTS Patients with PLE (n = 6) with clinically proven pathological responses to UV-B exposure and normal erythemal sensitivity. Healthy volunteers (n =5) were recruited among students and hospital staff. MAIN OUTCOME MEASURES Expression of cytokines related to Langerhans cell migration (interleukin [IL] 1, IL-18,and tumor necrosis factor [TNF] α); TH2 responses(IL-4 and IL-10 ); and TH1 responses (IL-6, IL-12, and interferon γ). Double staining was performed for elastase (neutrophils), tryptase (mast cells),and CD36 (macrophages). RESULTS The number of cells expressing IL-1β and TNF-α was reduced in the UV-B–exposed skin of patients with PLE compared with the skinof healthy individuals (P