title: The monoclonal antibodies 18d7/91f2 recognize a receptor regulatory protein on mouse bone marrow stromal cells.
abstract: Two monoclonal antibodies 18D7 and 91F2 were developed by immunizing rats with the mouse bone marrow-derived osteogenic cell line MN7. Hybridomas secreting rat antibodies against MN7 cell surface markers were selected by flow cytometry analysis. Both the monoclonal antibody 18D7 and the monoclonal antibody 91F2 are directed against the same cell surface antigen present on MN7 cells. Here, we report on the immunopurification of the 18D7/91F2 antigen and its identification as the prostaglandin F2 alpha receptor regulatory protein (FPRP). FPRP is expressed as a single messenger RNA (mRNA) of approximately 6 kilobases (kb) in MN7 cells and is differentially expressed in developing osteogenic cultures of bone marrow cells of the mouse. However, addition of the monoclonal antibodies 18D7 and 91F2 to these cultures did not inhibit bone formation in vitro. Both monoclonal antibodies reacted with mouse stromal cell lines established from bone marrow, thymus, spleen, and mandibular condyles. Immunohistochemical analysis of mature tibia of mice using the monoclonal antibody 18D7 revealed the presence of a distinct population of bone marrow cells close to trabecular and endosteal bone surfaces. In the central bone marrow, hardly any positive cells were found. In 17-day-old fetal mouse radius 18D7 immunoreactivity was restricted to cells in the periosteum in close vicinity to the bone collar. Mature osteoblasts, osteoclasts, osteocytes, growth plate chondrocytes, and mature macrophages were all negative. Taken together, these results suggest that FPRP plays a role in the osteogenic differentiation process.
authors.affiliation: Department of Biochemistry, University of Antwerp, Wilrijk, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Weng
authors.forename: N
authors.initials: N
authors.lastname: Falla
authors.forename: R
authors.initials: R
authors.lastname: Van den Heuvel
authors.forename: J
authors.initials: J
authors.lastname: Raymackers
authors.forename: M
authors.initials: M
authors.lastname: Karperien
authors.forename: R
authors.initials: R
authors.lastname: Van Bezooijen
authors.forename: P
authors.initials: P
authors.lastname: Van Vlasselaer
authors.forename: C
authors.initials: C
authors.lastname: Löwik
authors.forename: J
authors.initials: J
authors.lastname: Merregaert
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001854:Bone Marrow Cells / Q000166:cytology* / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D002478:Cells, Cultured; D008334:Mandible / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010012:Osteogenesis; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar; D011982:Receptors, Prostaglandin / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013154:Spleen / Q000166:cytology; D017154:Stromal Cells / Q000166:cytology* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology; D014158:Transcription, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D009363:Neoplasm Proteins; D011506:Proteins; C104480:Ptgfrn protein, rat; D011982:Receptors, Prostaglandin