Acute Effects of Whole-Body Proton Irradiation on the Immune System of the Mouse

Abstract Kajioka, E. H., Andres, M. L., Li, J., Mao, X. W., Moyers, M. F., Nelson, G. A., Slater, J. M. and Gridley, D. S. Acute Effects of Whole-Body Proton Irradiation on the Immune System of the Mouse. The acute effects of proton whole-body irradiation on the distribution and function of leukocyte populations in the spleen and blood were examined and compared to the effects of photons derived from a 60Co γ-ray source. Adult female C57BL/6 mice were exposed to a single dose (3 Gy at 0.4 Gy/min) of protons at spread-out Bragg peak (SOBP), protons at the distal entry (E) region, or γ rays and killed humanely at six different times thereafter. Specific differences were noted in the results, thereby suggesting that the kinetics of the response may be variable. However, the lack of significant differences in most assays at most times suggests that the RBE for both entry and peak regions of the Bragg curve was essentially 1.0 under the conditions of this study. The greatest immunodepression was observed at 4 ...