Increased burn-induced immunosuppression in lipopolysaccharide-resistant mice

Severe burns induce a state of immunosuppression, and the inflammatory resp onse after burn injury may play a role in this phenomenon. This study exami ned the effect of the inflammatory response to endotoxin on burn-induced im munosuppression and oxidative stress, An endotoxin-resistant mouse strain ( C3H/HeJ) and a normally responding mouse strain (C3H/HeN) were compared. Th e mice were separated into three groups of five animals for each experiment al day: (1) saline, (2) buprenorphine, and (3) buprenorphine and 20% total body surface area burn. All animals were fed ad libitum. The inflammatory r esponse was studied at 1, 4, 7, 10, and 14 days postburn, Proliferation of activated splenocytes in built mice was significantly lower on days 7, 10, and 14 for the C3H/HeJ strain and on days 4 and 10 for the C3H/HeN strain. Globally, C3H/HeJ presented stronger immune suppression than C3H/HeN. Oxida tive stress parameters (liver malonaldehyde, spleen metabolic activity, and thiol concentrations) were higher in endotoxin-resistant mice than in the control strain. Impairment of the inflammatory response was more pronounced and oxidative stress was greater in endotoxin-resistant burn mice than in normal burn controls. Buprenorphine administration was not related to depre ssion of these immune parameters. The inflammatory response following burn injury may be beneficial to the immune system. (C) 2000 Academic Press.