title: Role of splenic stroma in the action of bacterial lipopolysaccharides on radiation mortality: a study in mice carrying the Slj allele.
abstract: Slj/+ mice display a slight macrocytic anaemia due to a defect in their haemopoietic organ stroma. They have a deficient endogenous spleen colony (CFU-end) formation following sublethal doses of gamma-radiation compared with their normal +/+ littermates, which is likely to be due to the low pre-irradiation CFU-S content of the Slj/+ spleen. CFU-S in these congenic mice do not differ in their sensitivity to gamma-irradiation or stem cell-activating factor. While injection of +/+ mice with 10 micrograms of lipopolysaccharide-W (LPS) one day prior to irradiation led to a substantial increase in their survival, the survival of Slj/+ mice was only slightly increased. Irradiation induced a similar dose-related reduction in the numbers of CFU-S in the spleen and femora of LPS-injected Slj/+ mice compared to similarly treated +/+ mice when measured directly after irradiation. At Day 9 after irradiation, injection of LPS led to a significantly higher CFU-end formation and higher numbers of CFU-S and nucleated cells in the Slj/+ spleens compared to LPS-injected +/+ mice. No such differences in the radioprotective effect of LPS were observed in the +/+ and Slj/+ mice with respect to the splenic and femoral 59Fe-incorporation and the femoral CFU-S numbers at Day 9. These data strongly suggest a contribution by immigrating CFU-S to the CFU-S numbers and endogenous colony formation in at least the Slj/+ spleen after LPS injection and subsequent sublethal irradiation. The observations also imply that the splenic organ stroma may play a mediatory role in the radioprotective action of LPS. In addition, the data represent an extreme example of a lack of correlation between animal survival and haemopoietic parameters. Caution should be taken when applying endogenous colony counts as a means of screening potential anti-radiation drugs.
mesh_terms: D000748:Anemia, Macrocytic / Q000473:pathology; D000818:Animals; D001854:Bone Marrow Cells; D003114:Colony-Forming Units Assay; D004920:Erythropoiesis / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D005720:Gamma Rays; D006410:Hematopoiesis / Q000187:drug effects / Q000528:radiation effects*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000528:radiation effects; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D008817:Mice, Mutant Strains; D011836:Radiation Tolerance; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D012485:Salmonella typhi; D013154:Spleen / Q000166:cytology / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D011837:Radiation-Protective Agents