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The Effect of Chronic Treatment of Mice with Urocanic Acid Isomers
Author(s) -
ElGhorr Ali A.,
Norval Mary
Publication year - 1997
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1997.tb01936.x
Subject(s) - urocanic acid , immunosuppression , concanavalin a , epidermis (zoology) , cd8 , lymph node , in vitro , immunology , biology , immune system , lymphocyte , lymph , chemistry , medicine , endocrinology , microbiology and biotechnology , biochemistry , pathology , enzyme , anatomy , histidine
— Trans‐urocanic acid (trans‐UCA) accumulates in the upper layers of the epidermis and can be isomerized to cis‐ UCA by UV light irradiation. Cis ‐urocanic acid possesses immunosuppressive properties that have led to its consideration as one of the initiators of UV‐induced immunosuppression. High quantities of cis‐UCA persist in human skin for prolonged periods in the summer months. In the present study, mice were injected intradermaUy with trans ‐UCA and cis ‐UCA three times a week for 4 weeks in order to ascertain the long‐term effects of the presence of these compounds in the skin. The weight of mice and of their spleens were unaffected by the cis‐ or trans ‐UCA treatment. A decrease in thymus weight, accompanied by an increase in lymph node weight, was detected in the cis ‐UCA‐treated mice compared with trans ‐UCA‐treated mice and untreated controls. A net accumulation of lymphocytes and dendritic cells (DC) in lymph nodes was evident following cis ‐UCA treatment but the percentage of both CD4+and CD8+lymphocytes as well as Ia+DC remained constant among the different treatment groups, indicating that there was no specific migration or proliferation of a particular subset of cells. The in vitro lymphoproliferative response of lymph node cells to the mitogen concanavalin A was significantly sup pressed by cis ‐UCA treatment. The density of Langerhans cells in the epidermis of the ears was not altered by the chronic cis ‐UCA treatment. However, chronic cis‐ UCA treatment did suppress the mixed skin lymphocyte reaction response utilizing epidermal cells from the ears (an uninjected area of skin), indicating a systemic suppression. Compared with trans ‐UCA treatment, chronic cis ‐UCA treatment did not cause a significant reduction in the contact hypersensitivity response to oxazolone or the delayed hypersensitivity response to herpes simplex virus. Thus, chronic treatment with cis ‐UCA led to the suppression of some, but not all, of the immune parameters that are affected by UVB irradiation.