iCi/iis/i-Urocanic-Acid-lnduced Suppression of Contact Hypersensitivity iniMonodelphis domestica/iIs Prevented by Ultraviolet A Radiation/Photoreactivating Light

摘要

The suppression of contact hypersensitivity by UVB (280ndash;320 nm) radiation can be prevented by photoreactivating light (PRL; 320ndash;400 nm) in the opossum Monodelphis domestica, implicating epidermal DNA lesions as the immunosup-pressive impairment. However, contact hypersensitivity can also be suppressed in the opossum with exogenous cis-urocanic acid, a molecule which is produced in UVB-irradiated epidermis and is a second potential mediator of photo-immunosuppression apparently independent of UVB-induced DNA damage. Here we demonstrate that irradiation of opossums with PRL either before or following treatment with exogenous cis-urocanic acid, significantly reduced the degree of immunosuppression. This suggests that, in addition to its capacity to initiate post-UVB-exposure epidermal DNA repair, the PRL waveband can induce an immunoprotective product, as yet unidentified, in opossum epidermis.