Interleukin 10 (IL-10) has been shown to decrease the production of pro-inflammatory cytokines such as IL-1, IL-6, and tumor necrosis factor α (TNF-α) in vitro. The authors tested whether IL-10's ability to suppress these cytokines confers it the capacity to protect mice from lipopolysaccharide (LPS)-induced shock, a monokine-mediated inflammatory reaction. They found that a single injection of 0.5–1 μg of recombinant murine IL-10 protected BALB/c mice from lethal intraperitoneal endotoxin injection, whether administered concurrently with or 30 minutes after the endotoxin. This protective effect was reversed by prior injection of neutralizing anti-IL-10 antibodies and correlated with a significant reduction in endotoxin-induced TNF-α release. These findings suggest that IL-10 may be a promising candidate for treating bacterial sepsis and other inflammatory conditions.Interleukin 10 (IL-10) has been shown to decrease the production of pro-inflammatory cytokines such as IL-1, IL-6, and tumor necrosis factor α (TNF-α) in vitro. The authors tested whether IL-10's ability to suppress these cytokines confers it the capacity to protect mice from lipopolysaccharide (LPS)-induced shock, a monokine-mediated inflammatory reaction. They found that a single injection of 0.5–1 μg of recombinant murine IL-10 protected BALB/c mice from lethal intraperitoneal endotoxin injection, whether administered concurrently with or 30 minutes after the endotoxin. This protective effect was reversed by prior injection of neutralizing anti-IL-10 antibodies and correlated with a significant reduction in endotoxin-induced TNF-α release. These findings suggest that IL-10 may be a promising candidate for treating bacterial sepsis and other inflammatory conditions.