TY - JOUR T1 - Characterization of Interleukin-1α Binding to Mouse Brain Endothelial Cells JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 665 LP - 670 VL - 291 IS - 2 AU - William A. Banks Y1 - 1999/11/01 UR - http://jpet.aspetjournals.org/content/291/2/665.abstract N2 - In vivo studies have shown that interleukin (IL)-1α binds to and is transported across brain endothelial cells, whereas in vitro studies have shown that brain endothelial cells respond to IL and contain mRNA for the IL-type 1 receptor. However, these binding sites have yet to be characterized. Herein, we used murine brain microvessels to characterize the binding of IL labeled with 125I. Binding was temperature- and time-dependent with maximal binding after 4 h of incubation at 37°C. The amount of radioactivity determined by HPLC to represent intact 125I-labeled murine IL-1α at 4 h was ∼100% in the incubation fluid and 80 to 90% for radioactive material recovered from the incubated cells.Bmax was 0.955 fmol and theKd was 292 pM for human 125I-IL and binding was displaced by interleukin-1β and interleukin-1 receptor antagonist but not by tumor necrosis factor α. Binding was dependent on magnesium and glucose. Incubation with antibodies showed that the binding site was not identical with the IL-type 1 receptor but closely resembled the blood-brain barrier transporter. These results show that murine brain endothelial cells have specific binding sites for IL and that these sites more closely resemble the transporter than the type 1 receptor. The American Society for Pharmacology and Experimental Therapeutics ER -