title: Polymorphic light eruption: an immunopathological study of evolving lesions.
abstract: Polymorphic light eruption (PLE) papules were successfully induced on previously affected sites in 11 out of 14 patients with PLE 4-20 h after single exposures to suberythemogenic doses of solar simulated radiation. Histological examination of biopsies performed 1 h, 5 h, 24 h, 72 h and 144 h post-irradiation revealed onset within 5 h of perivascular cellular infiltration. The infiltrate was dominated by lymphocytes in both early and established lesions, without evident epidermal pathology. Immunohistochemistry demonstrated a predominance of CD4+ cells in lesions up to 72 h post-induction, but later biopsies were dominated by a CD8+ infiltrate. Significantly increased numbers of dermal macrophages and CD1b+ cells were detected 1 h and 5 h post-irradiation, respectively. These findings are consistent with a delayed type hypersensitivity response underlying the pathogenesis of polymorphic light eruption.
authors.affiliation: Institute of Dermatology, St. Thomas' Hospital, London, U.K.
authors.forename: P G
authors.initials: PG
authors.lastname: Norris
authors.forename: J
authors.initials: J
authors.lastname: Morris
authors.forename: D M
authors.initials: DM
authors.lastname: McGibbon
authors.forename: A C
authors.initials: AC
authors.lastname: Chu
authors.forename: J L
authors.initials: JL
authors.lastname: Hawk
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed; D007111:Immunity, Cellular; D008297:Male; D008875:Middle Aged; D010787:Photosensitivity Disorders / Q000276:immunology* / Q000473:pathology; D012867:Skin / Q000276:immunology / Q000473:pathology