The duration of Grenz ray-induced suppression of allergic contact dermatitis and its correlation with the density of Langerhans cells in human epidermis.

Recent investigations have shown that Grenz rays can suppress the allergic contact dermatitis reaction completely and that Langerhans cells, identified by OKT6 antibodies and electron microscopy, disappear from the epidermis at the same time. It is not known for how long this suppression lasts. This has been investigated in 28 nickel-sensitive patients who were given Grenz rays (3 Gy) on the back, once a week for 3 weeks. The patients were then divided into four groups and tested with patch tests for nickel at 1, 7, 14 and 21 days after the last Grenz ray treatment. Biopsies were taken from positive patch test sites, and from the corresponding opposite control. They were labelled with OKT6 antibodies to detect Langerhans cells. The patch test reactions were suppressed and the Langerhans cell density was decreased initially. These changes were restored after 3 and 6 weeks, respectively. The results show that the effect of Grenz rays on eczematous reactions extends to a maximum of 3 weeks and imply that Langerhans cells are necessary for the elicitation of the efferent phase of allergic contact dermatitis.