Lethal shock is inducible by lipopolysaccharide but not by superantigen in mice with retrovirus-induced immunodeficiency syndrome

Abstract

The retrovirus-induced murine AIDS (MAIDS) shares many features with human AIDS. Here, we examined the susceptibility of mice with MAIDS to staphylococcal enterotoxin-triggered shock. Following sensitization with D-galactosamine (D-Gal), mice with MAIDS were resistant to the otherwise lethal effect of superantigen staphylococcal enterotoxin A (SEA). Peak IL-2 levels in these mice after D-Gal/SEA challenge were 10-fold higher than those in uninfected controls, and concurrently, IL-10 levels rose markedly with reduction of circulating IL-1 and IFN-gamma. Treatment with neutralizing anti-IL-10 mAb before D-Gal/SEA challenge led to increased IFN-gamma levels in mice with MAIDS, and resulted in a dose-dependent mortality. In contrast, mice with MAIDS were more susceptible to the toxicity of bacterial endotoxin LPS than were uninfected controls. Administration of 100 micrograms LPS alone induced 50% lethality in mice infected with MAIDS virus 8 wk previously but not in uninfected controls. Administration of 10 micrograms LPS caused acute shock in D-Gal-sensitized mice with MAIDS. Peak TNF-alpha levels in these mice after LPS challenge were increased more than 10-fold, whereas IL-10 levels were one-third of those after SEA challenge. Moreover, serum IFN-gamma was undetectable in uninfected controls and rose to 1063 +/- 483 pg/ml in mice with MAIDS 4 h after LPS challenge. These results suggest that aberrant profiles of cytokine production are crucial in determining fatal outcome in these two types of septic shock in MAIDS.