Role of IL-10 in inflammation. Studies using cytokine knockout mice.

Interleukin-10 (IL-10) inhibits the synthesis of proinflammatory cytokines known to be involved in fever, including IL-1, IL-6, and tumor necrosis factor-alpha. We hypothesized that IL-10 modulates lipopolysaccharide (LPS)-induced fever in mice. Body temperature was measured by biotelemetry. Swiss Webster mice injected with recombinant murine IL-10 (rmuIL-10) were resistant to fever induced by a low dose of LPS (100 micrograms/kg, i.p.) and to the hypothermic and febrile effects of a high (septic-like) dose of LPS (2.5 mg/kg, i.p.). Injection of rmuIL-10 alone had no effect on afebrile body temperature of Swiss Webster mice. IL-10 knockout mice showed an exacerbated and prolonged fever in response to a low dose of LPS (50 micrograms/kg, i.p.) compared to their wild-type counterparts. These data support the hypothesis that IL-10 acts as an endogenous cryogen during LPS-induced fever in mice.