Abstract
Although comprehensive genome analysis is effective in biological studies, such qualitative approach is not suitable for the analysis of subtle biological effect of low dose/low dose rate radiation. Here we statistically synthesize data from identical experiments, and analyze effect of continuous low dose rate gamma-irradiation on murine immune system. C57BL/6 mice were ip immunized with allogenic mastocytoma, P815. Mice were killed 10 days after the immunization, and assessed peripheral blood leukocyte number, and spleen cell populations, as well as P815-specific antibody titer in their serum, and P815-specific cytotoxic T lymphocytes activity in spleen. Splenocyte gene expression including cytokine genes and stress-responding genes, was also quantified by quantitative PCR. Mice were continuously irradiated with dose rate between 0.003-0.2 mGy/h during the experiments from 7 days before the immunization. Results obtained from 10 independent experiments were statistically synthesized through meta-analysis. We found that low dose-rate irradiation significantly increased spleen cell number, especially CD8 positive killer T cells, and non-lymphocyte populations. It also increased transcription of CSF-2 and TNFalpha. Principal component analysis among these parameters suggests that antibody production and cell population were coordinately changed depending on the irradiation. Our results suggest that statistical synthesis of independent experiments is a powerful strategy to increase statistical power in evaluation of subtle biological effect of low dose/low dose rate radiation.
