MINIMUM DOSES OF ULTRAVIOLET RADIATION REQUIRED TO INDUCE MURINE SKIN EDEMA and IMMUNOSUPPRESSION ARE DIFFERENT and DEPEND ON THE ULTRAVIOLET EMISSION SPECTRUM OF THE SOURCE*

Abstract

Many photoimmunological studies have used UV radiation sources that emit nonsolar UV spectral energy and UV doses based on nonimmunological endpoints, e.g. erythema and skin edema. Interpretation of these data has led to misunderstanding when extrapolated to hypothetical effects in humans exposed to solar UV. The purpose of this study was to: (1) establish UV dose response relationships for murine skin edema and immunosuppression, and (2) determine how different UV spectra affect these relationships. Back skin and ear minimum edema doses (MEdD) for Kodacel‐filtered FS20 sunlamp UV (290–400nm) were greater than two‐fold higher than those for unfiltered FS20 sunlamp UV (250–400nm). Xenon arc solar simulator UV (295–400nm) MEdD were > 10‐fold higher than those for unfiltered sunlamp UV. Back skin and ear MEdD differed two‐ to five‐fold between C3H/ HeN, SWR/J and HRA/Skh‐1 mice. The minimum immunosuppression doses (MISD) in C3H mice showed similar UV source spectrum dependence. The solar simulator UV MISD was 5.4‐ and 1.5‐fold higher than for unfiltered and Kodacel‐filtered sunlamp UV MISD, respectively. Furthermore, MISD were from 3‐ to 50‐fold higher than the MEdD for the three UV sources. The UV bioeffectiveness spectra indicated that UVC energy (250–290nm) contributed 12% and 18%, respectively, of the total skin edema and immunosuppression UV energy. These data demonstrate the variability in UV sensitivity among mouse strains, the significant differences between murine MEdD and MISD and how these differences are influenced by nonsolar regions (below 295 nm) of the UV spectrum.

Failure of physiologic doses of pure UVA or UVB to induce lesions in photosensitive cutaneous lupus erythematosus: implications for phototesting

“…Interestingly, we found that the MED in our patient and control populations using a UVB radiation source with a kodacel filter to minimize UVC contamination was similar to those found in previous studies using unfiltered UVB radiation (18,(20)(21)(22). Several authors have postulated that the UVC component of the UVB radiation sources commonly used in phototesting studies makes a significant contribution to the erythema response (25,26,29). After minimizing UVC, we expected to see slightly higher MED values than those previously reported in SCLE populations.…”

“…In addition to administering physiologic doses of radiation, we also sought to define accurately the spectra of our radiation sources and to minimize contamination of our sources with heat, infrared light, and UVC radiation. Recently, several authors have argued for the routine inclusion of spectral data in every phototesting study (33,34,29). Only a few phototesting cutaneous LE studies give the percentage of UV radiation emitted from the bulbs (17,22).…”

The Effect of Suntan Parlor Exposure on Delayed and Contact Hypersensitivity

“…It should be noted that the relative contribution of UVA versus UVB radiation to the modulation of traditionally studied markers of immune function, i.e. suppression of CHS sensitization, delayed hypersensitivity responsiveness and circulating immune cell numbers and function in these and other studies in humans (32)(33)(34)(35)(37)(38)(39)(40) and in animal models (41)(42)(43)(44)(45) remain quite controversial.…”

Dose-Response on the Chemopreventive Effects of Sarcophine-Diol on UVB-Induced Skin Tumor Development in SKH-1 Hairless Mice

“…UVB is frequently used to induce photocarcinogenesis in animals. UVB radiation induces characteristic DNA damage on skin cells, immunosuppression, and modulation of various signal transduction pathways which can lead to cell proliferation, transformation, and cell death [6,7,8]. …”