Purification and characterization of a novel soluble receptor for interleukin 1.
Affinity chromatography and reverse-phase high-performance liquid chromatography was used to purify a soluble interleukin 1 beta (IL-1 beta) specific binding protein from the supernatant of a human B cell line, Raji. The purified protein specifically bound 125I IL-1 beta forming a 60-kD complex in nonreducing conditions and a 70-kD complex in reducing conditions. Binding was found to be displaceable by mature human and murine IL-1 beta and human 31-kD IL-1 beta propeptide, but not displaceable by human and murine IL-1 alpha or human IL-1 receptor (IL-1R) antagonist. Ligand blotting revealed a 47-kD molecule that specifically bound IL-1 beta. Measurement of binding affinity of the cell surface Raji IL-1R (Kd = 2.2 nm) and the Raji soluble (s)IL-1R (Kd = 2.7 nm) demonstrated a similar affinity for 125I IL-1 beta. Purified sIL-1R inhibited binding of IL-1 beta to cell lines with both type I (80 kD) and type II (65 kD) IL-1Rs, but did not interfere with IL-1 alpha binding. This natural sIL-1R may function as an important regulatory molecule of IL-1 beta in vivo.
Symons
J A
JA
Department of Medicine and Pharmacology, University of Sheffield, Royal Hallamshire Hospital, United Kingdom.
Eastgate
J A
JA
Duff
G W
GW
D002460:Cell Line; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000302:isolation & purification* / Q000378:metabolism; D017472:Receptors, Interleukin-1
D007375:Interleukin-1; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1