Abstract

BACKGROUND:

The major goal of this study was to determine whether radiation significantly alters bone marrow-derived cell distribution and mass of sensitive organs after challenge with lipopolysaccharide (LPS).

MATERIALS AND METHODS:

C57BL/6 mice were exposed whole-body to 0 or 3 gray (Gy) gamma-radiation (60Co) and injected intraperitoneally with 0.1 ml saline or 1 mg/kg LPS (E. coli serotype 0111:B4) 10 days later. Subsets from each group were euthanized at 60 min and 1, 7 and 14 days post-injection for analyses.

RESULTS:

Body mass was low 1 day after LPS, especially in irradiated animals. LPS-induced splenomegaly and hepatomegaly were attenuated by radiation, whereas thymic atrophy was enhanced. However, radiation had no effect on LPS-induced changes in oxygen radical production by liver phagocytes. The numbers of all major leukocyte populations (lymphocytes, monocyte-macrophages, granulocytes) were altered by both radiation and LPS at virtually all time points of testing. In general, the LPS-induced changes in leukocytes were diminished by radiation. Significant radiation x LPS interactions were especially prominent at day 1 after LPS administration. In contrast, mice receiving both radiation and LPS had lower red blood cell (RBC) and platelet counts than those receiving either agent alone.

CONCLUSION:

The data show that radiation had a highly significant influence on LPS-induced changes in mass of several body organs, leukocytes, RBC, and platelets, and thus may increase severity of infection due to Gram-negative bacteria.