Urocanic Acid Enhances IL-10 Production in Activated CD4+ T Cells

• Published in: The Journal of immunology (1950) Vol. 161; no. 7; pp. 3237 - 3241
• Main Authors: Holan, Vladimir, Kuffova, Lucia, Zajicova, Alena, Krulova, Magdalena, Filipec, Martin, Holler, Petr, Jancarek, Alexander
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.10.1998
• Subjects: Adjuvants, Immunologic - pharmacology; Animals; Antigen Presentation - drug effects; CD4-Positive T-Lymphocytes - drug effects; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - metabolism; Female; Gene Expression Regulation - drug effects; Gene Expression Regulation - immunology; Interleukin-10 - biosynthesis; Interleukin-10 - genetics; Lymphocyte Activation - drug effects; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Spleen - cytology; Spleen - immunology; Stereoisomerism; T-Lymphocyte Subsets - drug effects; T-Lymphocyte Subsets - metabolism; Urocanic Acid - pharmacology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.161.7.3237

The immunosuppressive effects of UV radiation have been well documented. This suppression has been attributed to the action of the cis form of urocanic acid (UCA), a photoproduct of trans-UCA, a natural constituent of the skin. Here, we show that mouse spleen cells preincubated with cis-UCA have a diminished proliferative response to allogeneic cells in MLC and to stimulation with anti-CD3 mAb. Cells preincubated with cis-UCA also had a decreased ability to serve as APC and to stimulate the proliferation of allogeneic lymphocytes in MLC. Simultaneously, the production of IL-2 and IFN-gamma by cells preincubated with cis-UCA was decreased. However, IL-10 gene expression and IL-10 protein secretion by spleen cells stimulated in the presence of cis-UCA were significantly enhanced. The principal cell population displaying the cis-UCA-induced elevated production of IL-10 was CD4+ T cells, which were shown to be a direct target of cis-UCA action. This was also supported by the observation that production of IL-10 by stimulated splenic non-T cells or by macrophages was not altered by cis-UCA. The enhanced production of IL-10 by activated CD4+ T cells may represent a novel pathway of UVB radiation-induced, cis-UCA-mediated immunosuppression. We suggest that the elevated production of IL-10 by activated CD4+ T cells may account for the suppressor T cell phenomena described in UV-irradiated recipients.