Interleukin-1 Receptors in Mouse Kidney: Identification, Localization, and Modulation by Lipopolysaccharide Treatment

The cytokine interleukin-1 (IL-1) has a variety of effects in the kidney involving induction of nephritis and renal injury. In addition, recent reports suggest that IL-1 regulates natriuresis and renin secretion in the kidney. To examine the potential sites of action of IL-1 in the kidney, we used iodine- 125-labeled recombinant human interleukin-la ([125I]IL-la) to identify and characterize IL-1 receptors in crude membrane preparations of mouse (C57BL/6) kidney. The binding of [125I] IL-la was linear over a broad range of membrane protein concentrations, saturable, reversible, and of high affinity, with an equilibrium dissociation constant (Kd) of 66 ± 10 pM and a maximum number of binding sites of 1.04 ± 0.24 fmol/mg protein. In competition studies, recombinant human IL-lα, recombinant human IL-1β, and a weak IL-1β analog (IL-ljβ+) inhibited [125I]IL-lα binding to mouse kidney in parallel with their relative bioactivities in the T-cell comitogenesis assay, with inhibitory binding affinity constant (Kj) ...