Effects of irradiation on cytokine production in a mouse model of Behçet's disease.

OBJECTIVE Low-dose whole-body irradiation is known to have anti-inflammatory effects. The objectives of this study were to verify that cytokine augmentation is induced by irradiation in vivo, and to assess the effectiveness of radiation in treating Behçet's disease (BD). METHODS Whole-body and half-body irradiation with single doses of 10cGy, 2Gy and 10Gy were delivered to normal mice, and cytokine and chemokine levels were analyzed in PBMC and sera. BD-like mice were treated with low-dose, half-body 10cGy irradiation. RESULTS In normal mice, PBMC cytokine mRNA levels peaked four days after irradiation. Of the cytokines and chemokines examined, the levels of IL-4, IL-6, IL-12p40, TNF-alpha, TGF-b, MIP-1alpha and IL-18 were all influenced by radiation treatment. Of these, IL-4, an ameliorating factor for BD, was the most elevated following low-dose irradiation (10cGy group). FACS analysis showed intracellular IL-4-staining of 7.24+/-0.92% of PBMC from irradiated mice compared to 1.3+/-0.1% from non-irradiated, normal mice (p<0.005). Serum IL-4 levels were also significantly increased (6.08+/-1.7 pg/ml) relative to control (1.83+/-0.8; p<0.005). CONCLUSION Augmentation of cytokine production may contribute to the anti-inflammatory effects of low dose irradiation and amelioration of BD symptoms in this mouse model.