Radiation and secondary immune response to lipopolysaccharide

The purpose of this study was to determine whether secondary immune responses to lipopolysaccharide (LPS) were altered by exposure to radiation.

C57BL/6 mice were irradiated (60Co, gamma-rays) to 0 or 3 Gray (Gy) and injected intraperitoneally with LPS on days 10 and 42 thereafter. Subsets were euthanized 0-14 days after the second injection for analyses.

The data show numerous radiation-induced effects, as well as some significant interactions among radiation, LPS, and day of analysis. Among the most striking were changes in thymus mass, circulating lymphocytes, monocytes, granulocytes, and specific lymphocyte subpopulations, erythrocyte counts, hematocrit, and platelet counts and volume. Spontaneous blastogenesis and oxidative burst capacity of phagocytic cells, however, were relatively normal.

The findings indicate that exposure to radiation at a spaceflight relevant dose can influence the distribution of certain leukocyte populations in response to a secondary challenge with LPS.