Abstract
Quantitative evaluation of biological responses to gamma radiation at low doses or at low dose rates is not sufficiently investigated. We acquired iterative experimental data of biological reaction in cell level to gamma radiation of low dose/low dose rate, and analyzed them using meta-analysis to evaluate quantitatively the effects.
Cytotoxic T cells were induced in C57BL/6 mice by intraperitoneal injection of P815 cells (2x107 cells/mouse). Mice were killed 10 days after the immunization, and antigen-specific cytotoxic T cell activity in the spleen was determined as percent lysis (effector to target ratio = 40), lytic unit (LU) per 104 splenocytes, or LU per mouse. One LU was defined as cytotoxic activity giving 10 % percent lysis. Mice were continuously irradiated at 4, 21 or 174 uGy/h for 17 days, from 7 days before the immunization throughout the experiment. These data were statistically and quantitatively analyzed by meta-analysis.
Synthesized effects of the experiments which were obtained by fitting a fixed-effects model to the data considering their variances showed no significant difference between irradiated samples and control samples. However, the data showed heterogeneity according to the radiation doses.
