Monoclonal antibody against interferon-gamma (ifn-gamma) inducing factor (ifig, il-18)

Abstract

A protein which induces the IFN-γ production by immunocompetent cells and has a molecular weight of 19,000±5,000 daltons on SDS-PAGE or gel filtration method and a pI of 4.8±1.0 on chromatofocusing. The protein is isolated from mouse liver and can be purified by a monoclonal antibody specific to it. The monoclonal antibody can be also used for assaying the protein.

We claim: 
     
         1 . A monoclonal antibody which specifically binds to IGIF or IL-18 consisting of the amino acid sequence of SEQ ID NO:2, wherein Xaa is Met or Thr; which substantially adsorbs said IGIF or said IL-18 but does not substantially adsorb proteins other than said IGIF or said IL-18; and which affords a purified IGIF or IL-18 with a purity of at least 95% when used in immunoaffinity chromatography. 
     
     
         2 . A monoclonal antibody, which is obtainable by immunizing mammals using a protein consisting of the amino acid sequence of SEQ ID NO:2, wherein Xaa is Met or Thr, or an antigenic fragment thereof as an antigen,
 collecting antibody-producing cells from the mammals,   hybridizing thus collected antibody-producing cells with cells that infinitely proliferate,   cloning hybridomas capable of producing said antibody,   culturing the clones in nutrient culture media, and   collecting the monoclonal antibody from the resultant cultures.   
     
     
         3 . A process for preparing a monoclonal antibody, which comprises the steps of:
 immunizing mammals using a protein consisting of the amino acid sequence of SEQ ID NO:2, wherein Xaa is Met or Thr, or an antigenic fragment thereof as an antigen;   collecting antibody-producing cells from the mammals;   hybridizing thus collected antibody-producing cells with cells that infinitely proliferate;   cloning hybridomas capable of producing said antibody;   culturing the clones in nutrient culture media; and   collecting the monoclonal antibody from the resultant cultures.   
     
     
         4 . A kit for detecting the presence of IGIF or IL-18 in a sample, which comprises a monoclonal antibody of  claim 1  labeled with radioactive substance, enzymes and/or fluorescent substance.