Proteins and methods for producing the proteins

A method of producing an osteoclastogenesis inhibitory factor protein comprising the steps of:

• (a) cultivating human fibroblast cells;
• (b) producing conditioned medium of said fibroblast cells;
• and
• (c) isolating said factor from said fibroblast cell conditioned medium by a combination of ion-exchange, affinity, and reverse phase chromatography, wherein said factor comprises an internal amino acid sequence as provided in SEQ. ID. No. 1, 2, or 3.

A recombinant protein which inhibits osteoclast differentiation and/or maturation, expressed from a cDNA encoding an amino acid sequence as provided in Seq. ID No. 4, said protein comprising the following properties:

• (a) molecular weights as determined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of approximately 60 kD under reducing conditions, and approximately 60 kD (a monomer) and 120 kD (a homodimer) under non-reducing conditions;
• (b) high affinity to cation-exchange resins and heparin derivatized substrates;
• (c) inhibitory activity for osteoclast differentiation and/or maturation, wherein said activity is decreased by heating said protein at about 70° C. for about 10 min. or at about 56° C. for about 30 min., and wherein said activity is lost by heating at about 90° C. for about 10 min.;
• and
• (d) an internal amino acid sequence as provided in Seq. ID No. 1, 2 or 3.