Method of identifying cells expressing a protein having pre-B cell growth-supporting ability

Abstract

A gene encoding a novel membrane protein polypeptide having pre-B cell growth-supporting ability, and a novel membrane protein polypeptide consisting of 180 amino acid residues having pre-B cell growth-supporting ability or a part of it. A method for producing said novel membrane protein polypeptide by preparing transformants by transforming a host cell with a vector containing said gene and culturing said transformants. A monoclonal antibody recognizing said novel membrane protein polypeptide. The above gene encodes the membrane protein having pre-B cell growth-supporting ability. The homogeneous and purified novel membrane protein polypeptide can be produced in large quantities and in addition, monoclonal antibodies recognizing said polypeptide can be produced; thus it becomes possible to identify rheumatoid arthritis (RA) and also prepare reagents for the clinical diagnosis thereof.

1 - 7 . (canceled)  
     
     
         8 . A method for identifying a synovial cell comprising: 
 contacting a synovial cell with an antibody for a time and under conditions suitable for binding of the antibody to the synovial cell,    and measuring binding,    wherein said antibody has a positive reactivity against cell lines U937 and K562 and recognizes a polypeptide consisting of the amino acid sequence shown in SEQ ID NO: 1, said polypeptide having pre-B cell growth-supporting ability.    
     
     
         9 . The method of  claim 8 , wherein said synovial cell is from a subject having rheumatoid arthritis.  
     
     
         10 . A method for identifying a subject having rheumatoid arthritis comprising: 
 contacting a synovial cell from a subject suspected of having rheumatoid arthritis with an antibody for a time and under conditions suitable for binding, and    determining binding of said antibody to said synovial cell, wherein the occurrence of, or the amount of, binding identifies rheumatoid arthritis in said subject,    wherein said antibody has a positive reactivity against cell lines U937 and K562 and recognizes a polypeptide consisting of the amino acid sequence shown in SEQ ID NO: 1, said polypeptide having pre-B cell growth-supporting ability.