312-nanometer Ultraviolet B Light (Narrow-Band UVB) Induces Apoptosis of  T Cells within Psoriatic Lesions

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.

Evaluation of CD40, its ligand CD40L and Bcl-2 in psoriatic patients

“…Uncovering the influence of different methods of psoriasis treatment on the apoptosis of keratinocytes and T lymphocytes is the aim of an increasing number of studies [12]. Methotrexate and UVB radiation (312 nm) have been demonstrated to induce T lymphocyte apoptosis within psoriatic lesions [13,14].…”

Autoimmune Melanocyte Destruction in Vitiligo

“…Although it cannot be excluded that the selfdestruction and neural hypotheses are applicable in subsets of vitiligo patients, recently obtained evidence strongly indicates that this pigmentary disorder is an autoimmune disease. This statement is further appreciated when regarding the current clinical practice of vitiligo management; all of the nonsurgical vitiligo treatments with proven efficacy (Njoo et al, 1998) are based on immunosuppression (Cato and Wade, 1996;Hill et al, 1999;Krutmann and Morita, 1999;Ozawa et al, 1999). Thus, future investigations in vitiligo etiology should focus on finding the exact conditions that trigger and sustain this melanocyte-specific autoimmune response.…”

Selected aspects of apoptosis in psoriasis

“…apoptosis inducing factor), która koreluje ze zmniejszeniem grubości naskórka w obrębie zmian [44]. Wykazano również, że promieniowanie UVB oraz metotreksat indukują apoptozę limfocytów T w obrębie zmian łuszczycowych [45,46]. Odnotowano także znaczne nasilenie ekspresji FasL po naświetlaniach UVB [28] oraz w trakcie leczenia metodą Goeckermana [47].…”