Interleukin-1 (IL-1) receptor antagonist binds to the 80-kDa IL-1 receptor but does not initiate IL-1 signal transduction

DJ Dripps, BJ Brandhuber, RC Thompson… - Journal of Biological …, 1991 - Elsevier
DJ Dripps, BJ Brandhuber, RC Thompson, SP Eisenberg
Journal of Biological Chemistry, 1991Elsevier
The interleukin-1 receptor antagonist (IL-1ra) is a protein capable of inhibiting receptor
binding and biological activities of IL-1 without inducing an IL-1-like response. Equilibrium
binding and kinetic experiments show that IL-1ra binds to the 80-kDa IL-1 receptor on the
murine thymoma cell line EL4 with an affinity (KD= 150 pM) approximately equal to that of IL-
1 alpha and IL-1 beta for this receptor. However, IL-1ra is unable to induce two early events
associated with IL-1 activity. Surface-bound IL-1ra does not undergo receptor-mediated …
The interleukin-1 receptor antagonist (IL-1ra) is a protein capable of inhibiting receptor binding and biological activities of IL-1 without inducing an IL-1-like response. Equilibrium binding and kinetic experiments show that IL-1ra binds to the 80-kDa IL-1 receptor on the murine thymoma cell line EL4 with an affinity (KD = 150 pM) approximately equal to that of IL-1 alpha and IL-1 beta for this receptor. However, IL-1ra is unable to induce two early events associated with IL-1 activity. Surface-bound IL-1ra does not undergo receptor-mediated internalization, and IL-1ra does not activate the protein kinase activity responsible for down-modulation of the EGF receptor on the murine 3T3 fibroblast cell line. The failure to induce general, early responses characteristic of IL-1 indicates that IL-1ra is unlikely to act as an agonist on any cell expressing the 80-kDa receptor.
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