title: Stereospecific inhibition of human epidermal cell interleukin-1 secretion and HLA-DR expression by cis-urocanic acid.
abstract: UV radiation is known to photoisomerize trans-urocanic acid (trans-UCA) into a stable isomer, cis-urocanic acid (cis-UCA). To study the possible immunomodulatory effects of cis-UCA, the two isomers were added separately to different in vitro assays employing human epidermal cell suspensions or purified human peripheral T lymphocytes, supplemented with epidermal cells. Cis-UCA but not trans-UCA suppressed interleukin-1 (IL-1) production by epidermal cell suspensions in a dose-dependent fashion and diminished the number of HLA-DR positive epidermal cells to 61% of control values. An inhibitory effect on epidermal cell accessory function could be demonstrated with both isomers of UCA, but only if UVB-irradiated epidermis was used as a source for the epidermal cells. Taken together, the findings of our study lend indirect support to the concept of cis-UCA as a possible mediator of UV-radiation-induced immunosuppression.
mesh_terms: D000276:Adjuvants, Immunologic; D002478:Cells, Cultured; D004817:Epidermis / Q000187:drug effects / Q000276:immunology* / Q000528:radiation effects; D006681:HLA-D Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000378:metabolism; D007536:Isomerism; D007700:Kinetics; D007801:Langerhans Cells / Q000187:drug effects / Q000276:immunology; D008285:Major Histocompatibility Complex; D012867:Skin / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D014466:Ultraviolet Rays; D014560:Urocanic Acid / Q000494:pharmacology*
chemical_list: D000276:Adjuvants, Immunologic; D006681:HLA-D Antigens; D006684:HLA-DR Antigens; D007093:Imidazoles; D007375:Interleukin-1; D014560:Urocanic Acid