Thermal and behavioral effects of lipopolysaccharide and influenza in interleukin-1 beta-deficient mice

This study characterized body temperature (Tb), locomotor activity (Act), and feeding behavior under normal conditions and following injection with lipopolysaccharide (LPS) or inoculation with live influenza virus of transgenic C57/black mice deficient in interleukin-1 beta (IL-1 beta). Tb and Act in freely moving mice were measured by biotelemetry. Mice deficient in IL-1 beta had normal circadian rhythm of Tb but were less active than their control counterparts. Mice injected with LPS (2.5 mg/kg i.p.) responded with a prompt decrease of Tb, which lasted approximately 10 h, followed by a fever in which Tb reached a peak at approximately 24 h postinjection. There was no difference between groups in the early drop of Tb after the LPS; however, the 24-h peak of Tb was lower in IL-1 beta-deficient mice. The anorexic effects of LPS and influenza infection were similar in both groups of mice. In mice given influenza virus (17.5 plaque-forming units, median lethal dose), Tb and Act gradually decreased. The fall of Tb was smaller in the transgenic mice. The mice deficient in IL-1 beta displayed a higher mortality rate due to influenza infection than the control mice. We conclude that deficiency in IL-1 beta results in lower fever following the LPS injection and in impairment of the defense response to infection with influenza.