title: A new biochemical marker for joint injury. Analysis of YKL-40 in serum and synovial fluid.
abstract: We report the development of the first radioimmunoassay for YKL-40, a M(r) = 40 kDa protein which is secreted at high levels by human synovial cells and articular cartilage chondrocytes, and by the human osteosarcoma cell line MG63. This assay uses YKL-40 purified from the conditioned medium of MG63 cells as standard and tracer, and as antigen for immunizing rabbits. With this assay we have discovered high levels of YKL-40 antigen in serum and SF. The molecular weight of serum and SF YKL-40 is identical to purified YKL-40. To evaluate the possible utility of YKL-40 in the assessment of joint disease, we measured YKL-40 in serum and SF of 49 patients with various forms of inflammatory and degenerative joint disease and in the serum of 50 normal adults. The YKL-40 level in serum was significantly higher (P < 0.001) in the patients compared to the normal adults, but there was no difference in serum YKL-40 between the patients with inflammatory joint diseases and OA. The SF levels of YKL-40 were 15-fold higher than serum levels and there was a significant correlation (r = 0.55, P < 0.001) between YKL-40 concentration in SF and serum. Although the tissue distribution of YKL-40 secretion is presently unknown, these observations suggest that a major portion of serum YKL-40 in fact arises from the joint.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Biology, University of California, San Diego, La Jolla.
authors.forename: J S
authors.initials: JS
authors.lastname: Johansen
authors.forename: H S
authors.initials: HS
authors.lastname: Jensen
authors.forename: P A
authors.initials: PA
authors.lastname: Price
mesh_terms: D054392:Adipokines; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D015415:Biomarkers; D000071451:Chitinase-3-Like Protein 1; D005260:Female; D006023:Glycoproteins; D006801:Humans; D007596:Joints / Q000293:injuries*; D037102:Lectins; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods; D012216:Rheumatic Diseases / Q000097:blood; D013582:Synovial Fluid / Q000378:metabolism; D014947:Wounds and Injuries / Q000097:blood / Q000378:metabolism*
chemical_list: D054392:Adipokines; D015415:Biomarkers; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins; D011506:Proteins