An experimental study on the enhanced macrophage (Mφ) function in tumor-bearing mice treated with low dose radiation

C57BL/6J mice implanted with Lewis lung carcinoma cells in the right thighs were used as an experimental animal model and whole body irradiation (WBI) with 75 mGy X-rays was given at the 10 th day after tumor implantation. The authors detected the cytostasis function of peritoneal Mφ of the mice (with the method of 3H-TdR incorporation assay) and the levels of TNFα and IL-1β mRNA transcription (with the method of in situ hybridization immunohistochemistry) 18 hours after irradiation. The experiment showed that the cytostasis function of peritoneal Mφ of irradiated mice was significantly increased compared with that of the sham-irradiated mice (irradiated mice: 79.9 +- 4.2%, sham-irradiated mice: 52.9 +- 8.1%, p < 0.01). The levels of TNFα and IL-1β mRNA transcription were quantitatively measured with a scanning densitometry and the data showed that both the TNFα and IL-1β mRNR transcriptional levels of peritoneal Mφ of irradiated mice were much higher than those of sham-irradiated mice (p<0.01). The results mentioned above suggested that low dose radiation could markedly enhance the Mφ function in tumor-bearing mice and the enhanced Mφ function played an important role in the process of immuno enhancement and antitumor immune reaction induced by low dose radiation