title: Impact of total-body irradiation on the response to a live bacterial challenge.
abstract: OBJECTIVE
  Concern regarding radiation effects on human health continues to increase worldwide. Given that infection is a major cause of morbidity and mortality after exposure, the aim of this study was to evaluate decrements in immune cell populations using a mammalian model subjected to a live bacterial infection.
  
  
  METHODS
  C57BL/6 mice were exposed to total-body irradiation (TBI) with 3 Gy protons (70 cGy/min). One, 2, 4, 8 or 16 days later, subsets of mice were injected intraperitoneally with live Escherichia coli [055:K59(B5)]. Control groups received no radiation and vehicle (no bacteria). The mice were euthanized for analyses 90-120 min after injection of the bacteria.
  
  
  RESULTS
  There were no unexpected effects of radiation or E. coli alone. Despite dramatic radiation-induced decreases in all leukocyte populations in both the blood and spleen, irradiated mice were still able to respond to an immune challenge based on capacity to generate an oxidative burst and secrete inflammatory cytokines, i.e., tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). However, these responses were generally elevated above control values.
  
  
  CONCLUSIONS
  Together, these results suggest the possibility for enhanced inflammation-associated tissue injury and increased risk for chronic inflammation.
authors.affiliation: Department of Basic Sciences, Divisions of Radiation Research and Biochemistry and Microbiology, Loma Linda University and Medical Center , Loma Linda, CA , USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pecaut
authors.forename: Farnaz P
authors.initials: FP
authors.lastname: Baqai
authors.forename: Daila S
authors.initials: DS
authors.lastname: Gridley
mesh_terms: D000818:Animals; D049628:Body Size / Q000276:immunology / Q000528:radiation effects; D016207:Cytokines / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004906:Erythrocyte Count; D004926:Escherichia coli / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology / Q000528:radiation effects; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology / Q000276:immunology / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D050296:Microbial Viability; D009929:Organ Size / Q000276:immunology / Q000528:radiation effects; D010976:Platelet Count; D016897:Respiratory Burst / Q000276:immunology / Q000528:radiation effects; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000528:radiation effects; D014916:Whole-Body Irradiation / Q000009:adverse effects*
chemical_list: D016207:Cytokines; D000949:Histocompatibility Antigens Class II
keywords: Escherichia coli; Total-body irradiation; immune function; protons; time course