Protective effect of previous burn on murine endotoxemia

Major body burns suppress the immune system, at least temporarily. However, it has not been demonstrated that following recovery from burn injury, the burned subject can become immunocompetent. This study was designed to test this hypothesis. Swiss-Webster mice (25 +/- 2 gm) anesthetized with intraperitoneal pentobarbital sodium were given full thickness burns on a depilated area of the lower back with a stainless steel tube (2 cm diameter) at 100 C for 10 seconds. Control mice were anesthetized, depilated in the same manner, but sham burned. Six weeks later, (the burn wound was completely healed, and the mice weighed 33 +/- 4 gm) each animal was given 0.3 mg of Escherichia coli endotoxin (055:B5) in saline intraperitoneally. The 24- and 72-hour survivals for the control animals were 31/45 (69%) and 13/45 (29%), respectively; while the 24- and 72-hour survivals for the post burn mice was 26/27 (96%) and 14/27 (52%), respectively (P less than 0.05). All animals surviving 72 hours recovered. These data clearly demonstrate that the survival from endotoxemia is significantly increased in animals that have been previously burned. This observation indicates that the immune system is stimulated 6 weeks postburn.