Effect of UVB on Alloactivating and Antigen Presenting Capacity of Human Epidermal Langerhans Cells

Abstract

Human epidermal cell suspensions (EC) were obtained by the suction blister technique and enzyme digestion. EC were irradiated in microtitre plates with doses up to 510 mJ/cm2 (2.6 minimal erythemal dose (MED] by means of fluorescent light bulbs emitting a 280-320 nm continuous spectrum with a peak at 310 nm. Purified allogeneic T cells were added to the EC immediately or 24 h after radiation. Irradiated EC were pulsed with purified protein derivative (PPD) for 90 min immediately or 24 h after radiation and then cocultured with purified autologous T cells. PPD-pulsed EC were also irradiated before being cocultured with autologous T cells. Pretreatment of EC suspensions with anti-DR antiserum plus complement abolished both the alloactivating and the antigen-presenting capacity, indicating that the DR-positive Langerhans cells are mainly responsible for these functions. There were no differences in the number of DR-positive cells in EC before or immediately after radiation. A statistically significant and UV-dose-dependent reduction of the alloactivating ability of EC was found both when allogeneic T cells were added immediately and when they were added 24 h after radiation. Likewise, a significant and dose-dependent reduction of the PPD-specific T-cell response was obtained in cultures when using irradiated EC that were PPD-pulsed immediately or 24 h after radiation. EC that were first PPD-pulsed and then irradiated induced a significantly increased T-cell response after low UV doses (1 or 2 MED), whereas higher doses induced a significant reduction of the T-cell responses.

Comparative immunotoxicology of ultraviolet B exposure I. Effects ofin vitroandin situultraviolet B exposure on the functional activity and morphology of Langerhans cells in the skin of different species

“…It was demonstrated that, for instance, ICAM-1 expression on LC, which is important for (allo)antigenpresentation, 24 was very sensitive for UVB radiation. 22,25 In addition, possible delayed effects induced by UVB exposure could not be detected in the morphological studies, assessed 4 h after exposure.…”

“…We used the same epidermal sheets to investigate the effects of in vitro and in situ UVB exposure on the stimulatory capacity of epidermal cells (EC), measured in a mixed skin lymphocyte response (MSLR) assay. 22 The statistical analysis of the data was performed using linear and non-linear regression methods in which the MSLR response was presented as a function of UVB dose.…”

Langerhans cells are initiators of the immunosuppressive effect of ultraviolet B radiation

“…In addition, these observations suggested that the unresponsiveness induced by local exposure to low doses of UVB was due to a loss in the APC function of LC. This latter interpretation was supported in subsequent studies conducted in several laboratories in which UVB irradiation in vitro (single doses of 25-600 J/m 2) was shown to cause human or mouse EC (containing LC) to lose their ability to stimulate antigen-specific proliferation of T cells [1,16].…”

Ultraviolet‐B Phototherapy Is Successful in Japanese Patients with Early‐Stage Mycosis Fungoides

“…Although the precise mechanism of UVB phototherapy in MF treatment remains unclear, recent studies have demonstrated that UVB suppresses the alloactivating and antigen-presenting capacity of Langerhans cells (16)(17)(18)(19) and enhances interleukin-1 and -6 production though human keratinocytes (19)(20)(21). In addition, increased amounts of tumor necrosis factor have been detected from human keratinocytes after UVB irradiation (20,22).…”