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.