Interleukin-1 pretreatment protects against endotoxin-induced hypotension in rabbits: association with decreased tumor necrosis factor levels.

Abstract

Rabbits were infused with either low-dose recombinant human interleukin (IL)-1 beta or vehicle 16 h prior to receiving lipopolysaccharide (LPS). In controls pretreated with vehicle, mean arterial pressure decreased to 68% of the baseline value by 90 min after LPS infusion and remained low for the duration of the study period. In IL-1-pretreated animals, a similar decrease in mean arterial pressure to 69% was observed at 60 min but returned to 90% of baseline after 180 min (P < .05). IL-1-pretreated animals showed no significant rise in serum tumor necrosis factor after LPS infusion compared with vehicle-treated animals (P < .05). Rabbits were pretreated as above with IL-1 and, 40 h later, plasma was transfused into a second group of rabbits just prior to LPS infusion. An infusion of post-IL-1 plasma did not reduce LPS-induced hypotension. Thus, pretreatment with IL-1 reduces the hypotension in response to LPS by a mechanism that is not plasma-mediated but that is associated with reduced serum tumor necrosis factor levels.