Cloning and expression of interleukin-18 binding protein

Interleukin-18 binding protein is a novel glycoprotein that we successfully cloned and expressed. First, murine interleukin-18 binding protein was pur ified from the sera of mice with endotoxin shock using ligand affinity chro matography. The murine interleukin-18 binding protein cDNA was cloned after RT-PCR using mixed primer pair sequences based on partial murine interleuk in-18 binding protein amino acid sequence analysis. Subsequently, human int erleukin-18 binding protein cDNA was cloned from cDNA libraries of normal h uman liver using murine interleukin-18 binding protein cDNA as a probe. Nex t, we transiently expressed recombinant human and murine interleukin-18 bin ding proteins in COS-1 cells and purified them from culture supernatants. B oth recombinant interleukin-18 binding proteins did not exhibit species spe cificity and prevented interleukin-18 binding to its receptor. In addition, they inhibited interleukine-18 dependent IFN-gamma production from KG-1 ce lls effectively. These results suggest that the interleukin-18 binding prot ein may possess interleukine-18 antagonist activity. (C) 1999 Federation of European Biochemical Societies.