Single administration of lesion‐limited high‐dose (TURBO) ultraviolet B using the excimer laser: clinical clearing in association with apoptosis of epidermal and dermal T cell subsets in psoriasis

Abstract

We conclude that a single 10 MED dose of TURBO UVB is effective at reducing the severity and extent of psoriatic lesions. We hypothesize that the reason a single treatment is sufficient to clear a psoriatic plaque is that the 10 MED dose is able to deliver sufficient photons to a microanatomic area of the lesion where susceptible pathogenic T cell mechanisms are operative.

Plaque-based sub-blistering dosimetry: Reaching PASI-75 after two treatments with 308-nm excimer laser in a generalized psoriasis patient

“…This 42-year-old patient reached PASI 79 after only two treatments with excimer laser and concurrent use of topical clobetasol spray twice daily. While both general and targeted UVB application increases apoptosis of T cells in the skin and decreases the amount of antigen presenting cells (9,10), it seems the administration of high doses of light may decrease the inflammatory response in the skin to a much greater extent, potentially leading to longer remission times (6). Certainly, the use of clobetasol spray may have contributed to the effectiveness of the high-dose excimer laser by not only enhancing the treatment of the psoriasis itself, but by possibly discouraging or decreasing any phototoxic reactions caused by the laser.…”

“…Administering anywhere from 8 to 16 multiples of MED to psoriatic plaques has resulted in clearance at that location in as little as one treatment, as well as longer remission rates than when much lower doses are used (5)(6)(7). Based on these earlier observations, we proposed a new excimer laser dosing protocol called ''Plaque-based Sub-blistering Dosimetry'' in which the patient's psoriatic plaque, rather than uninvolved skin, is tested with incrementally increasing doses to determine the dose at which blistering is observed, and then treated just below that dose -at what we termed the ''Plaque Sub-blistering Dose''.…”

Does imiquimod pretreatment optimize 308‐nm excimer laser (UVB) therapy in psoriasis patients?

“…In our previous laser UVB study (Kagen et al . ), we examined patients at 2, 4 and 8 weeks post‐UVB treatment. Based on the results of the previous study, the majority of response occurred by 4 weeks post‐treatment.…”

Evolution of targeted phototherapy for psoriasis

“…The apoptosisinducing capacity of a 308-nm excimer laser was higher than that of NB-UVB and almost four-times higher than the calculated value, attributing the clinical effectiveness of excimer laser therapy. Kagen et al investigated T-cell depletion and apoptosis in the skin of psoriasis after a single dose of 10 minimal erythema dose (MED) of a 308-nm excimer laser [20]. A single 10 MED irradiation induced reduction of memory/effector T cells infiltrating lesional epidermis and dermis and apoptosis and activation of caspase in lesional T cells.…”