Radiation and primary immune response to lipopolysaccharide: Lymphocyte distribution and function

Introduction: Lipopolysacchayide (LPS) is a major cause of septic shock and death due to infection with Gram-negative bacteria. The purpose of this study was to quantify the effects of whole-body irradiation on lymphocyte populations during response to challenge with LPS. Materials and Methods: C57BL/6 mice (n=10/group) were irradiated whole-body with 3 gray (Gy) γ-rays in a single fraction at 0.8 Gy/min. LPS (E. coli serotype 0111:B4) at 1 mg/kg was injected intraperitoneally 10 days later and mice were euthanized at 60 min and days 1, 7, and 14 post-inoculation for analyses. Results: Significant interactions between radiation and LPS were noted in circulating and splenic lymphocyte subpopulations, including T-, B-, and NK-cells, particularly at the early time points. There were significant interactions on circulating, but not splenic, CD62L+ T-cell populations. However, there were no interactions on CD62L+ B-cells. Finally, there were significant interactions in both early and late blastogenic responses. Conclusion: The data support that response to infection with Gram-negative bacteria may be significantly compromised by exposure to ionizing radiation.