THERMAL AND BEHAVIORAL-EFFECTS OF LIPOPOLYSACCHARIDE AND INFLUENZA ININTERLEUKIN-1-BETA-DEFICIENT MICE

This study characterized body temperature (T-b), locomotor activity (A ct), and feeding behavior under normal conditions and following inject ion with lipopolysaccharide (LPS) or inoculation with live influenza v irus of transgenic C57/black mice deficient in interleukin-1 beta (IL- 1 beta). T-b and Act in freely moving mice were measured by biotelemet ry. Mice deficient in IL-1 beta had normal circadian rhythm of T-b but were less active than their control counterparts. Mice injected with LPS (2.5 mg/kg ip) responded with a prompt decrease of T-b, which last ed similar to 10 h, followed by a fever in which T-b reached a peak at similar to 24 h postinjection. There was no difference between groups in the early drop of T-b after the LPS; however, the 24-h peak of T-b was lower in IL-1 beta-deficient mice. The anorexic effects of LPS an d influenza infection were similar in both groups of mice. In mice giv en influenza virus (17.5 plaque-forming units, median lethal dose), T- b and Act gradually decreased. The fall of T-b was smaller in the tran sgenic mice. The mice deficient in IL-1 beta displayed a higher mortal ity 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.