Interleukin 1 stimulates fibroblasts to synthesize granulocyte-macrophage and granulocyte colony-stimulating factors. Mechanism for the hematopoietic response to inflammation.

IL-1 is a family of polypeptides which play a critical role in the inflammatory response. Characteristics of this response include an enhanced release of bone marrow neutrophils, activation of circulating and tissue-phase phagocytes, and enhanced production of neutrophils and monocytes. We have sought to understand the hematopoietic response to acute and chronic inflammatory states on a cellular and molecular level. Colony-stimulating factors (CSFs) are glycoproteins involved in the production and activation of neutrophils and monocytes in vitro and in vivo. We have found that quiescent dermal fibroblasts constitutively release granulocyte-macrophage CSF (GM-CSF), granulocyte CSF (G-CSF), and macrophage CSF in culture, and that picomolar concentrations of the inflammatory mediator IL-1 stimulate by at least fivefold the transcription and release of GM-CSF and G-CSF. These findings establish the role of IL-1 in the hematopoietic response to inflammation through the stimulation of the production and release of GM-CSF and G-CSF.