Abstract
[Purpose] It is known that electromagnetic waves, particularly ionizing radiation and UVB, have significant effects of immune system. This study was designed to evaluate the effect of electromagnetic waves on autoimmune reaction using a mouse Graves' model. [Methods] Graves' hyperthyroidism was induced by immunizing mice with adenovirus expressing TSHR 2x at 3 wk intervals, and hyperthyroidism was confirmed by measuring T4 using sera obtained 2 wks after 2nd immunization. Electromagnetic waves were given to mice at a single dose (0.5 Gy or 10 kJ/m2) 1 wk before or after 1st immunization, or at fractionated doses (0.1 Gy or 1 kJ/m2, 2x/wk for 6 wks). TSHR Abs were determined with FRTL5 cells (for stimulatory Abs) or CHO cells expressing TSHR (for total Ab titers). IFN-γ production from SPC was measured with ELISA kit. T cell subpopulations in SPC including CD4+CD25+ regulatory T cells (Treg) were evaluated by flow cytometry.[Results] Only a single administration of UVB after 1st immunization suppressed T4 and stimulatory Ab titers, and IFN-γ production in immunized mice as compared to non-irradiated, immunized mice. The titers of total TSHR Abs were not decreased. The number of Treg was significantly increased by fractionated, but not a single dose of, UVB. [Conclusion] UVB irradiation after the immunization significantly suppressed development of Graves' hyperthyroidism without affecting systemic immune function. Involvement of Treg in this suppression is however unlikely.
