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Background: Although PUVA treatment of psoriasis is more effective than conventional or broad-band UVB phototherapy, two small studies have suggested that narrow-band or TL-01 phototherapy may have a therapeutic effect equal to PUVA. If confirmed, this would be of considerable importance as TL-01 therapy is likely to be considerably safer in the long term than PUVA., Objective: The purpose of this study was to compare PUVA with narrow-band (TL-01) phototherapy in psoriasis., Methods: We studied 100 patients with plaque-type psoriasis who were randomly allocated to twice-weekly treatment with PUVA or narrow-band UVB., Results: Clearance of psoriasis was achieved in a significantly greater proportion of patients treated with PUVA (84%) than with TL-01 (63%) (P =.018), and with significantly fewer treatments (median number of treatments for clearance with PUVA, 16.7; with TL-01, 25.3; P =.001). Only 12% of those treated with TL-01 were clear of psoriasis 6 months after finishing treatment compared with 35% for PUVA (P =.002)., Conclusion: When given twice weekly, PUVA is more effective for psoriasis than narrow-band UVB phototherapy.

Background: PUVA treatment of psoriasis is usually given with broad-band fluorescent UVA lamps. Narrow-band UVB exposure after oral methoxsalen has been shown to achieve a greater therapeutic response in psoriasis than identical UVB exposure given without psoralen., Objective: The purpose of this study was to compare conventional PUVA with psoralen-UVB therapy in psoriasis., Methods: We studied 100 patients with plaque-type psoriasis who were randomly selected to receive either conventional psoralen-UVA or psoralen-UVB treatment., Results: No significant difference was found between the two treatments in the proportion of patients whose skin cleared during treatment or in the number of exposures required for clearance of psoriasis. As expected, the cumulative UV dose for clearance was smaller in the group treated with UVB compared with those receiving UVA. Side effects and disease status at 3 months after the end of treatment were similar for the two groups., Conclusion: Psoralen-UVB treatment of psoriasis is as effective as conventional PUVA. The mechanism of psoralen-311 nm UVB action on psoriasis requires study to predict the long-term safety of this treatment.

In an attempt to improve the prediction of PUVA erythemal sensitivity, we have examined, in 251 patients, the relationship between the minimal phototoxic dose (MPD) and a number of variables, including skin type, ingested dose of 8-methoxypsoralen (8-MOP) and history of previous PUVA treatment. The MPD was determined by phototesting 2 h after ingestion of crystalline 8-MOP, given at a standard dose of 0.6 mg/kg (calculated to the nearest 10 mg). No reaction to the highest dose of UVA used for phototesting occurred in 16% of cases; the dose of 8-MOP was significantly associated with non-response. In the patients in whom an erythemal response was obtained, a significant association was found between the MPD and the variables of skin type, ingested dose of 8-MOP, and history of previous PUVA treatment. Thus, by taking these factors into account, a more accurate prediction can be made of an individual patient's erythemal sensitivity to PUVA than relying on skin type alone. That erythemal sensitivity is affected by the ingested dose of 8-MOP (even when all patients received 0.6 mg/kg) suggests that conventional psoralen dosing according to body weight is not ideal.

We have compared the effectiveness of oral 8-methoxypsoralen photochemotherapy (PUVA) using ultraviolet fluorescent lamps with peak emission at either 325, 352 or 370 nm in the treatment of 24 patients with psoriasis. The forearms of each patient were treated three times weekly with two of the three lamps. The erythemal sensitivity of each patient was tested before the first treatment to ensure that equally erythemal doses of radiation were given from each of the lamps. A side-to-side comparison was used to assess response to treatment at weekly intervals for the 6 weeks of the trial. The lamp with peak emission at 325 nm was shown to be significantly superior to either of the other lamps in terms of response assessed at weekly intervals, and time to clearance of psoriasis. An action spectrum, constructed from the median doses required for clearance of psoriasis using each of the lamps, showed that the effectiveness of the radiation decreased exponentially with increasing wavelength throughout the UVA waveband, such that radiation at 320 nm was an order of magnitude more effective than at 360 nm. This suggests that lamps with peak emission around 325 nm will be more effective than those conventionally used in PUVA units with a peak emission at 352 nm. Lamps with peak emission around 325 nm are also highly effective in the treatment of psoriasis with phototherapy alone. Thus a single treatment unit containing these lamps could be used either for PUVA or ultraviolet phototherapy of psoriasis, avoiding duplication or irradiation equipment.

People receiving therapy with either 8-methoxypsoralen plus long wavelength ultraviolet radiation (PUVA) or medium wavelength ultraviolet radiation (UVB) have been studied to see whether their unresponsiveness to the contact sensitizer dinitrochlorobenzene (DNCB) is a form of immunological tolerance. It was confirmed that both PUVA and UVB therapy impair sensitization by DNCB:4/13 PUVA-treated and 9/29 UVB-treated psoriatic subjects became sensitized by a dose of DNCB which sensitizes 100% of untreated patients. Subjects unsuccessfully sensitized during PUVA therapy could subsequently be sensitized perfectly normally. Subjects unsuccessfully sensitized during UVB therapy showed slight impairment of subsequent sensitization which was not statistically significant, and which was probably a persistent effect of UVB exposure. In conclusion, the temporary unresponsiveness seen in human subjects exposed to antigens during PUVA or UVB therapy is not due to immunological tolerance.