The impact of mouse strain on iron ion radio-immune response of leukocyte populations.
OBJECTIVE
Exposure to various forms of radiation, including iron ions that have an exceptionally high biological effectiveness, is an inevitable consequence of spaceflight. However, genetic background can significantly influence the response to radiation and hence also the overall health of crewmembers. The major goal of this study was to compare leukocyte population responses in two strains of mice that differ in susceptibility to radiation: C57BL/6 (resistant) and CBA/Ca (susceptible).


METHODS
The mice were whole-body irradiated with 0, 50, 200, or 300 cGy (56)Fe(26) (1 GeV) at approximately 1 Gy/min and euthanised on days 4 and 30 thereafter for analyses. Analyses included body and organ masses (spleen, liver, thymus, lungs), distribution of leukocyte populations in blood and spleen, red blood cell and platelet characteristics, expression of surface molecules (CD11b, CD54), and spontaneous and mitogen-induced blastogenesis.


RESULTS
There were main effects of Dose and Dose x Day interactions on virtually all quantified parameters in both strains of mice. In contrast, there were relatively few Dose x Strain and three-way interactions. Strain-related interactions involved changes in circulating phagocytic populations, erythrocytes, and liver mass.


CONCLUSIONS
The data demonstrate that genetic background can modify certain immune-related parameters after exposure to heavy particle radiation. The possible implications of these findings are discussed.
Pecaut
Michael J
MJ
Department of Radiation Medicine, Radiation Research Laboratories, Loma Linda University and Medical Center, Loma Linda, CA 92354, USA. mpecaut@dominion.llumc.edu
Gridley
Daila S
DS
D000818:Animals; D015703:Antigens, CD / Q000528:radiation effects; D001792:Blood Platelets / Q000528:radiation effects; D001835:Body Weight / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004781:Environmental Exposure; D055633:Immune System Phenomena / Q000276:immunology / Q000502:physiology / Q000528:radiation effects*; D007504:Iron Radioisotopes / Q000633:toxicity*; D007962:Leukocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects*; D008099:Liver / Q000528:radiation effects; D008213:Lymphocyte Activation / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D009929:Organ Size / Q000528:radiation effects; D009928:Organ Specificity / Q000528:radiation effects; D010586:Phagocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D011836:Radiation Tolerance; D013045:Species Specificity; D013997:Time Factors; D014916:Whole-Body Irradiation / Q000009:adverse effects*
D015703:Antigens, CD; D007504:Iron Radioisotopes