The sensitivity of Langerhans cells to simulated solar radiation in basal cell carcinoma patients.

The role of Langerhans cells (LC) in host resistance against the induction and growth of nonmelanoma skin cancers is still obscure. The purpose of this study was to investigate the sensitivity of LC to simulated solar radiation in patients with basal cell carcinoma (BCC). Thirty-four patients (31-74 years old) with at least one histologically diagnosed BCC on a sun-exposed area and 21 healthy volunteers (29-62 years old) were included in the study. Patients and control subjects were given 10 graded doses of simulated solar UV radiation (10-75 mJ/cm2) on the lower back using a 12S solar simulator with a WG 320 filter. Twenty-four hours later, the minimal erythema dose (MED) was determined and shave biopsies were taken from the site given 1.25 X MED and from adjacent, unirradiated skin. Epidermal sheets were stained for LC using the ATPase method. The mean value of the MED of the BCC patients was 25 +/- 2 mJ/cm2 and that of controls was 29 +/- 3 mJ/cm2 (p greater than 0.05). The number of ATPase+ LC was significantly decreased (p less than 0.05), and their morphology was altered in the irradiated skin of nearly all individuals. However, there was no significant difference in the average reduction of LC in the patients (32% +/- 3%) compared with that of control subjects (32% +/- 4%). The depletion of LC ranged from 0% to 74% in different individuals, all of whom were given 1.25 MED. Furthermore, no correlation was found between the percentage decrease in ATPase+ cells and the dose of UV radiation required to produce erythema. Our results indicate that the ability of UV radiation to cause erythema was unrelated to the magnitude of its effects on LC number or morphology. Second, the morphologic alterations of LC in BCC patients after UV irradiation do not differ from those observed in normal individuals. Third, as a group, patients with BCC do not have a significantly lower MED than cancer-free subjects.