312-nanometer ultraviolet B light (narrow-band UVB) induces apoptosis of T cells within psoriatic lesions

J Exp Med. 1999 Feb 15;189(4):711-8. doi: 10.1084/jem.189.4.711.

Abstract

Narrow-band (312 nm) ultraviolet B light (UVB) is a new form of therapy for psoriasis, but its mechanism of action is unknown. In a bilateral comparison clinical study, daily exposure of psoriatic plaques to broad-band UVB (290-320 nm) or 312-nm UVB depleted T cells from the epidermis and dermis of psoriatic lesions. However, 312-nm UVB was significantly more depleting in both tissue compartments. To characterize the mechanism of T cell depletion, assays for T cell apoptosis were performed on T cells derived from UVB-irradiated skin in vivo and on T cells irradiated in vitro with 312-nm UVB. Apoptosis was induced in T cells exposed to 50-100 mJ/cm2 of 312-nm UVB in vitro, as measured by increased binding of fluorescein isothiocyanate (FITC)-Annexin V to CD3(+) cells and by characteristic cell size/granularity changes measured by cytometry. In vivo exposure of psoriatic skin lesions to 312-nm UVB for 1-2 wk also induced apoptosis in T cells as assessed by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) reaction in tissue sections, by binding of FITC-Annexin V to CD3(+) T cells contained in epidermal cell suspensions, and by detection of apoptosis-related size shifts of CD3(+) cells. Induction of T cell apoptosis could be the main mechanism by which 312-nm UVB resolves psoriasis skin lesions.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Annexin A5 / metabolism
  • Apoptosis / radiation effects*
  • CD3 Complex / analysis
  • Cell Size
  • Epidermis / immunology
  • Epidermis / pathology
  • Epidermis / radiation effects
  • Erythema / etiology
  • Female
  • Humans
  • In Situ Nick-End Labeling
  • Male
  • Psoriasis / immunology
  • Psoriasis / pathology*
  • Psoriasis / radiotherapy*
  • Skin / immunology
  • Skin / pathology
  • Skin / radiation effects*
  • Ultraviolet Rays
  • Ultraviolet Therapy*

Substances

  • Annexin A5
  • CD3 Complex