title: Anti-lubricin monoclonal antibodies created using lubricin-knockout mice immunodetect lubricin in several species and in patients with healthy and diseased joints.
abstract: Lubricin, encoded by the gene PRG4, is the principal lubricant in articulating joints. We immunized mice genetically deficient for lubricin (Prg4-/-) with purified human lubricin, and generated several mAbs. We determined each mAb's binding epitope, sensitivity, and specificity using biologic samples and recombinant lubricin sub-domains, and we also developed a competition ELISA assay to measure lubricin in synovial fluid and blood. We found the mAbs all recognized epitopes containing O-linked oligosaccharides conjugated to the peptide motif KEPAPTTT. By western blot, the mAbs detected lubricin in 1 μl of synovial fluid from several animal species, including human. The mAbs were specific for lubricin since they did not cross-react with other synovial fluid constituents from patients with camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP), who genetically lack this protein. The competition ELISA detected lubricin in blood samples from healthy individuals but not from patients with CACP, indicating blood can be used in a diagnostic test for patients suspected of having CACP. Lubricin epitopes in blood do not represent degradation fragments from synovial fluid. Therefore, although blood lubricin levels did not differentiate patients with inflammatory joint disease from healthy controls, epitope-specific anti-lubricin mAbs could be useful for monitoring disease activity in synovial fluid.
authors: Howard Hughes Medical Institute and Department of Genetics, Case Western Reserve University, School of Medicine, Cleveland, OH, United States of America.
authors: Minrong
authors: M
authors: Ai
authors: Howard Hughes Medical Institute and Department of Genetics, Case Western Reserve University, School of Medicine, Cleveland, OH, United States of America.
authors: Yajun
authors: Y
authors: Cui
authors: Department of Pathology, Case Western Reserve University, School of Medicine, Cleveland, OH, United States of America.
authors: Man-Sun
authors: MS
authors: Sy
authors: Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA, United States of America.
authors: David M
authors: DM
authors: Lee
authors: Department of Emergency Medicine, Rhode Island Hospital, Providence, RI, United States of America.
authors: Ling Xiu
authors: LX
authors: Zhang
authors: Department of Emergency Medicine, Rhode Island Hospital, Providence, RI, United States of America; School of Engineering, Brown University, Providence, RI, United States of America.
authors: Katherine M
authors: KM
authors: Larson
authors: Department of Pathology, Boston Children's Hospital, Boston, MA, United States of America.
authors: Kyle C
authors: KC
authors: Kurek
authors: Department of Emergency Medicine, Rhode Island Hospital, Providence, RI, United States of America; School of Engineering, Brown University, Providence, RI, United States of America.
authors: Gregory D
authors: GD
authors: Jay
authors: Howard Hughes Medical Institute and Department of Genetics, Case Western Reserve University, School of Medicine, Cleveland, OH, United States of America; Howard Hughes Medical Institute and Orthopaedics Research Laboratories, Boston Children's Hospital, and Departments of Genetics and Orthopaedic Surgery, Harvard Medical School, Boston, MA, United States of America.
authors: Matthew L
authors: ML
authors: Warman
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D001177:Arthropathy, Neurogenic / Q000097:blood*; D016022:Case-Control Studies; D060905:Coxa Vara / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005260:Female; D006023:Glycoproteins / Q000097:blood / Q000172:deficiency* / Q000235:genetics / Q000276:immunology*; D006228:Hand Deformities, Congenital / Q000097:blood*; D006801:Humans; D007596:Joints / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008875:Middle Aged; D009842:Oligopeptides / Q000737:chemistry; D009844:Oligosaccharides / Q000737:chemistry; D013582:Synovial Fluid / Q000378:metabolism; D013585:Synovitis / Q000097:blood*; D000099158:Proteoglycan 4
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D006023:Glycoproteins; D009842:Oligopeptides; D009844:Oligosaccharides; D000099158:Proteoglycan 4
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