Constitutively active aryl hydrocarbon receptor expressed in T cells increases immunization-induced IFN-γ production in mice but does not suppress Th2-cytokine production or antibody production

• Published in: International immunology Vol. 21; no. 7; pp. 769 - 777
• Main Authors: Nohara, Keiko, Suzuki, Takehiro, Ao, Kana, Murai, Hikari, Miyamoto, Yoshimi, Inouye, Kaoru, Pan, Xiaoqing, Motohashi, Hozumi, Fujii-Kuriyama, Yoshiaki, Yamamoto, Masayuki, Tohyama, Chiharu
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.07.2009
• Subjects: AhR; TCDD; transcription factor; transgenic mice; TCDD; transcription factor; AhR; transgenic mice
• ISSN: 0953-8178; 1460-2377
• DOI: 10.1093/intimm/dxp045

The ligand-dependent transcription factor aryl hydrocarbon receptor (AhR) has been implicated in various immune functions. Our previous studies have shown that AhR activation by exposure of ovalbumin (OVA)-immunized mice to the potent ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increases immunization-induced IFN-γ production in the spleen and suppresses the production of Th2 cytokines and OVA-specific antibodies. In the present study, we used transgenic (Tg) mice that express a constitutively active mutant of aryl hydrocarbon receptor (CA-AhR) specifically in T-lineage cells to clarify the role of AhR activation in T cells in these reactions. The results of this study clearly demonstrated that AhR activation only in the T cells augments IFN-γ production upon OVA immunization. By contrast, production of Th2 cytokines and antibodies were not significantly suppressed by CA-AhR in the T cells. These results suggest that suppression of Th2 cytokines and antibodies production require AhR activation not only in T cells but also in other cell types as caused by TCDD exposure. Alternatively, these results may indicate that IFN-γ augmentation and Th2 cytokines and antibodies suppression depend on different ways of functions of AhR in the T cells and that CA-AhR does not replicate the suppressive effect of TCDD-activated AhR on Th2 cytokines and antibodies. Expression of CA-AhR in the T cells was also shown to increase the percentage of CD25+ cells among CD4+ cells in the thymus and spleen. Thus, studies using T-cell-specific CA-AhR Tg mice provide a way to dissect the role of AhR in individual cell types and how the AhR functions.