The effects of low-dose X-irradiation on the oxidative burst in stimulated macrophages

Purpose: Local irradiation with a dose of around 0.5 Gy is an effective treatment of acute necrotizing inflammations. The hypothesis that low doses of X-rays modulate the oxidative burst in activated macrophages, which plays a major role in the acute inflammatory process, was tested. Materials and methods: Murine RAW 264.7 macrophages were stimulated with LPS/gammaIFN, PMA or zymosan and oxidative burst was measured using either DCFH-DA or by reduction of cytochrome-C. Radiation doses of 0.3-10 Gy were given shortly before or after stimulation. Results: Low X-ray doses of <1 Gy significantly reduced the oxidative burst in activated macrophages, whereas higher doses had little effect on oxidative burst. Conclusions: The modulation of oxidative burst by low radiation doses may contribute to the therapeutic effectiveness of low-dose radiotherapy of acute necrotizing inflammations.