INTERLEUKIN-4 REGULATES MESSENGER-RNA ACCUMULATION OF MACROPHAGE-COLONY STIMULATING FACTOR BY FIBROBLASTS - SYNERGISM WITH INTERLEUKIN-1-BETA

Summary. We demonstrate that macrophage‐colony stimulating factor (M‐CSF) is expressed in human fibroblasts at the mRNA and protein level. Following activation with both interleukin (IL)‐1β and IL‐4. fibroblasts synthesized M‐CSF transcripts detectable by Northern blot analysis with peak expression occurring at 8 h and 12 h, respectively. Exposure of fibroblasts to both cytokines resulted in M‐CSF protein release at 60 h of c. 500 U/ml (for IL‐1β) and 1000 U/ml (for IL‐4), relative to a control preparation of recombinant human M‐CSF in a murine bone marrow colony assay. Both interleukins synergized to enhance M‐CSF mRNA accumulation and their ability to induce M‐CSF transcripts could be abolished by treatment with specific neutralizing antibodies. These observations provide support for the idea that fibroblasts may control monocyte/macrophage development and function, and that IL‐1β and IL‐4 are involved in the regulation of this process. Copyright © 1990, Wiley Blackwell. All rights reserved