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

Abstract

Ultraviolet (UV) B-induced morphological and functional changes in the skin of mice, rats and humans were investigated. Changes in the morphological structure of Langerhans cells (LC), the major antigen-presenting cells in the skin, using confocal laser scanning microscopy, were found in mouse and rat skin after in situ exposure to high doses of UVB radiation (FS40) (3-9 kJ/m2). Similar UVB doses failed to induce alterations in the morphological structure of human LC. Alterations in the function of epidermal cells (especially LC) were studied, using the mixed skin lymphocyte response (MSLR). In vitro UVB exposure of epidermal cells (EC), derived from the skin of the different species, revealed that low doses of UVB radiation impaired the stimulatory capacity of these cells dose-dependently; mouse epidermal cells were most UVB-susceptible, while human cells were least UVB susceptible. For suppression of the stimulatory capacity of EC after in situ UVB exposure of skin tissue, higher doses of UVB radiation than the in vitro UVB exposure were needed in all species tested. Also in this in situ set-up mouse epidermal cells were most UVB-susceptible, and human epidermal cells were least UVB-susceptible. The magnitude of differences in susceptibility for UVB-induced changes in the stimulatory capacity of EC after in situ and after in vitro exposure experiments was similar. Firstly, it may be concluded that UVB impairs the functional activity of LC at a lower dose than that which alters the morphology of these cells. Secondly, it is clear that epidermal cells, especially LC, from the skin of rodents are more susceptible to UVB than epidermal cells derived from human skin. It is important to account for these differences in susceptibility when data on the effects of UVB radiation on the immune system in rodents are extrapolated to humans.

Effects of narrowband UV‐B on pharmacodynamic markers of response to therapy: an immunohistochemical study over sequential samples

“…This observation, which is in contrast to experimental data, has been previously reported when therapeutic‐based doses were administered 27–28 . Nevertheless, it should be kept in mind that UV‐B impairs the functional activity of Langerhans cells at a lower dose than that needed to alter their morphology and number 29–32 …”

Ultraviolet A Radiation Suppresses an Established Immune Response: Implications for Sunscreen Design

“…Based on our measurements of the intensity of solar UV radiation present in sunlight (in September midday sun, Houston TX, 30°N latitude), we estimate that 30 min of sunlight exposure will provide an equivalent UV dose in humans. Because some have reported that rodent antigen-presenting cells are three to four times more susceptible to the immune suppressive effects of UV radiation than human antigen-presenting cells (Goettsch et al, 1998b), care must be employed when extrapolating results from animal models to humans. It is interesting to note, however, that the same authors subsequently reported that 90 min of sunlight exposure (in July, 40°N latitude) caused 50% suppression of the immune response to Listeria monocytogenes in humans (Goettsch et al, 1998a).…”

Effective Narrow-Band UVB Radiation Therapy Suppresses the IL-23/IL-17 Axis in Normalized Psoriasis Plaques

“…Additionally, some studies have found a decrease Langerhans cell numbers after therapy (Murphy et al , 1993; Tjioe et al , 2003), although others have not found a significant decrease (Carrascosa et al , 2007; Erkin et al , 2007). Nevertheless, it is clear that NB-UVB impairs in vitro antigen presentation by both murine DCs and human Langerhans cells, rendering them tolerogenic rather than stimulatory (Baadsgaard et al , 1990; Goettsch et al , 1998; Murphy et al , 1993; Noonan et al , 1988; Simon et al , 1991). Thus, NB-UVB can suppress a broad range of immune cells.…”