PUVA treatment in chromium hypersensitivity: effect on skin reactivity and lymphocyte functions

The management of oral lichen planus

OBJECTIVE

To review the current literature regarding the medical treatment of oral lichen planus (OLP).

DATA SOURCES

PubMed on-line Medline data searches were carried out for the years 1966-1998 to identify reports on therapy of OLP.

METHODS OF STUDY SELECTION

Single case reports or open trials were included if they covered new therapeutic approaches or suggested significant modifications of known treatment modalities. Review papers were limited to those dealing with the topic.

DATA EXTRACTION AND SYNTHESIS

Every paper was critically examined. Because of the great heterogeneity of the response criteria, many data could not be directly compared. Stronger weight was given to therapies that have proven to be effective under placebo-controlled research protocols. Attention was also drawn to potential and effective adverse effects of every drug used.

CONCLUSIONS

Among the various medications advocated for the treatment of OLP, several lack conclusive findings from adequately controlled trials. Mainly high-potency topical corticosteroids in an adhesive medium appear at present the safest and most efficacious. Adjuvant agents as antimycotics may be useful in topical steroid treatment. Systemic corticosteroids may be occasionally indicated for severe recalcitrant erosive OLP or for diffuse mucocutaneous involvement. Topical cyclosporine should be considered in steroid-unresponsive cases considering that its efficacy in OLP could be related to a systemic effect and its high cost. Classical PUVA therapy seems to have too many side effects; topical application of psoralen is promising but still experimental. Topically and systemically delivered retinoids combined with topical corticosteroids could improve the efficacy of these agents whereas complete remission is difficult to achieve with retinoids alone and they frequently cause adverse effects. Finally, there are only few data concerning the long-term effect of the medical treatments upon the course of OLP and we do not know if therapy influences the malignant evolution of OLP.

UV sunlight and patch test reactions in humans

No seasonal influence of UV sunlight on patch test reactions in humans over a period of 9 years of clinical practice was found in this retrospective study of almost 8000 patients. Although the mean UV monthly dose varies seasonally, up in the summer and down in the winter, no significant differences could be identified for patch test reactions, either for the mean number of positive test reactions or for the intensity of the skin reaction or for the id-like spread reactions seen in summer or winter. Furthermore, no short-term influences of UV exposure during the weekend preceding patch testing could be demonstrated. Therefore, reliable patch-test results can be expected at any season of the year from a general population, at least in Belgian-type climates.

Psoralen photochemotherapy

Psoralens and sunlight have been used by the Egyptians and Indians for hundreds of years for the treatment of vitiligo. The combination of oral psoralens and artificial ultraviolet A (PUVA) therapy was approved for the management of severe psoriasis by the Food and Drug Administration in 1982. Since then PUVA therapy has been found to be an effective modality in the treatment of many cutaneous conditions. When properly administered, the major short-term side effects are minimal. The long-term side effects may include an increased risk of squamous cell carcinoma, atypical cutaneous pigmentation, accelerated skin aging, and ophthalmologic abnormalities. By careful patient selection and limiting the cumulative UVA dosage and frequency by using combinations or alternative therapies, these side effects may be reduced. Continued reporting of carefully carried out long-term prospective studies will provide us with more knowledge of the long-term side effects of PUVA. In the meantime, for each patient on PUVA therapy the risk/benefit ratio should be carefully considered.

The effect of grenz rays on the expression of allergic contact dermatitis in man

To investigate the effect of grenz rays on the expression of allergic contact dermatitis, six patients hypersensitive to nickel were studied. They were given 3 Gy of grenz rays, once a week for 3 weeks, to a defined area of the back. Twenty-four hours after the last treatment serial dilution nickel patch tests were applied on the grenz-ray-treated area and on untreated control skin. There was an almost total suppression of the allergic contact dermatitis at the site of grenz ray treatment. Biopsy specimens were taken from nickel-challenged and unchallenged skin, both from the grenz-ray-treated area and from the control area. Different cell populations in epidermis and dermis were identified by monoclonal antibodies (Leu 2, 3, 4, 7, Leu M1, B1, OKT6). In the grenz-ray treated epidermis there was a pronounced reduction of OKT6-positive cells, regarded as Langerhans cells. No other differences were observed between control and grenz-ray-treated skin. Our results suggest that Langerhans cells might be required also for the effector phase of the allergic contact dermatitis.

Effect of a single UVB or PUVA exposure on immediate and delayed skin hypersensitivity reactions in humans. Correlation to erythemal response and Langerhans cell depletion

A single UVB or PUVA exposure given 4 days prior to skin testing affected skin responses both to contact allergens and to histamine and the histamine liberator, compound 48/80. The delayed contact hypersensitivity reactions were attenuated by UVB in 75% and by PUVA in 79% of the tests. The immediate skin reactions to histamine and compound 48/80 were diminished by UVB in 81% and by PUVA in 46% of the cases. While the epidermal Langerhans cell (LC) density was distinctly affected by irradiation, the attenuation of skin hypersensitivity reactions seemed to be independent of the degree of LC depletion. A significant correlation was, however, found between the strength of the erythemal reaction induced by the irradiation and the attenuation of the skin hypersensitivity test reactions; this was true for both delayed and immediate skin reactions in the case of UVB and for immediate skin reactions in the case of PUVA. The mechanism behind the attenuating effect of UV radiation on skin hypersensitivity reactions remains unknown, but it probably does not result from a stabilization of the mast cell membrane, as histamine and compound 48/80 induced reactions were suppressed to a similar extent.