312-nanometer ultraviolet B light (narrow-band UVB) induces apoptosis of T cells within psoriatic lesions.
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.
Ozawa
M
M
Laboratory for Investigative Dermatology, The Rockefeller University, New York 10021-6399, USA.
Ferenczi
K
K
Kikuchi
T
T
Cardinale
I
I
Austin
L M
LM
Coven
T R
TR
Burack
L H
LH
Krueger
J G
JG
D000328:Adult; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000528:radiation effects*; D017252:CD3 Complex / Q000032:analysis; D048429:Cell Size; D004817:Epidermis / Q000276:immunology / Q000473:pathology / Q000528:radiation effects; D004890:Erythema / Q000209:etiology; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D011565:Psoriasis / Q000276:immunology / Q000473:pathology* / Q000532:radiotherapy*; D012867:Skin / Q000276:immunology / Q000473:pathology / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014467:Ultraviolet Therapy