GM-CSF rapidly primes mice for enhanced cytokine production in response to LPS and TNF.

Subcutaneous administration of Granulocyte-macrophage-colony stimulating factor (GM-CSF) to mice enhanced LPS-induced cytokine production in the circulation (TNF, IL-6) and peritoneal cavity (IL-1 beta, IL-6). This effect was induced rapidly (within 1 h) and persisted for 4 h. Mice made leukopenic with cyclophosphamide retained the ability to respond to GM-CSF. In addition, TNF induced IL-6 production was also enhanced. These results demonstrate that GM-CSF has a pronounced priming effect on cytokine producing cells in vivo and raises the possibility that this cytokine may contribute to the pathogenesis of septic shock.