Soluble cytokine receptors appear to modify ligand concentrations by stabilizing ligands or by specifically inhibiting interactions of ligands with their membrane-bound receptors. Here we describe a new function of the soluble interleukin-1 receptor type I (IL-1sR I). This receptor induced a transient rise of intracellular free calcium concentration in human dermal fibroblasts in a dose-dependent fashion. Mobilization of calcium by IL-1sR I was abolished in the presence of an equimolar concentration of IL-1 receptor antagonist (IL-1ra). Neutralizing antibodies against IL-1β also abolished calcium mobilization stimulated with IL-1sR I indicating that IL-1β is involved. IL-1sR I bound with high affinity (K(d) 1-2 nM) to the fibroblasts. In addition, IL-1sR I enhanced expression of IL-6 and IL-8 mRNA. The observation that IL-1sR I can act as a ligand and agonist for membrane IL-1 extends the concept of the ligand-receptor functions of both IL-1 and IL-1sR I and adds a new dimension to the cytokine network. Copyright (C) 1998 Federation of European Biochemical Societies.
Spörri, B., Wiesmann, U. N., Ochsenbein, R. M., Loetscher, M., Waelti, E. R., Lottaz, D., & Bickel, M. (1998). Soluble IL-1 receptor type I binds to human dermal fibroblasts and induces calcium flux. FEBS Letters, 434(3), 283–288. https://doi.org/10.1016/S0014-5793(98)00995-8