title: Interleukin 1 stimulates granulocyte macrophage colony-stimulating activity release by vascular endothelial cells.
abstract: Studies designed to characterize monocyte-derived recruiting activity (MRA) a monokine that stimulates endothelial cells to produce granulocyte macrophage-colony-stimulating activity (CSA) by endothelial cells, show that it is a thermolabile protein of from 12,000 to 24,000 D which, on chromatofocusing, shows three separate peaks of eluted activity from pH 7.5 to 5.0. Because these and many other properties of MRA are identical to those of interleukin 1 (IL-1), we tested the hypothesis that MRA and IL-1 are identical. We cultured vascular endothelial cells with various concentrations of purified native and recombinant IL-1 (pI 7 form), then tested the endothelial cell supernatants for GM-CSA. Purified native IL-1 and recombinant IL-1 stimulated endothelial cells to release CSA. The MRA of native IL-1, recombinant IL-1, and unfractionated monocyte conditioned medium was neutralized by a highly specific rabbit anti-human IL-1 antiserum. Chromatofocusing fractions that contained MRA contained immunoreactive IL-1 on immunoblotting and the bioactivity was neutralized completely by treatment with the antiserum. We conclude that IL-1 induces the release of CSA by vascular endothelial cells, that IL-1 is constitutively produced by monocytes in vitro, and that MRA and IL-1 are biologically, biophysically and, immunologically identical.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004261:DNA Replication; D004727:Endothelium / Q000502:physiology*; D007375:Interleukin-1 / Q000032:analysis / Q000276:immunology / Q000502:physiology*; D007377:Interleukin-3 / Q000096:biosynthesis* / Q000378:metabolism / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D007375:Interleukin-1; D007377:Interleukin-3; D011994:Recombinant Proteins