Recognition of YKL-39, a human cartilage related protein, as a target antigen in patients with rheumatoid arthritis.
OBJECTIVE
To investigate whether autoimmunity to YKL-39, a recently cloned cartilage protein, occurs in patients with rheumatoid arthritis (RA).


METHODS
Autoantibody to YKL-39 was assayed by enzyme linked immunosorbent assay (ELISA) and western blotting in serum samples from patients with RA, systemic lupus erythematosus (SLE), and healthy donors, using recombinant YKL-39 protein. This reactivity was compared with that against a YKL-39 homologue, YKL-40 (human cartilage gp-39/chondrex), which has been reported to be an autoantigen in RA.


RESULTS
Autoantibody to YKL-39 was detected in seven of 87 patients with RA (8%), but not in serum samples from patients with SLE or healthy donors. YKL-40 reactivity was found in only one of 87 RA serum samples (1%), with no cross reactivity to YKL-39.


CONCLUSIONS
The existence of anti-YKL-39 antibody in a subset of patients with RA is reported here for the first time. Further, it was shown that the immune response to YKL-39 was independent of that to YKL-40. Clarification of the antibody and T cell responses to autoantigens derived from chondrocyte, cartilage, or other joint components may lead to a better understanding of the pathophysiology of joint destruction in patients with RA.
Sekine
T
T
Rheumatology, Immunology and Genetics Programme, Institute of Medical Science, St Marianna University, School of Medicine 2-16-1, Sugao, Miyamae-ku, Kawasaki, Kanagawa, 216-8512, Japan.
Masuko-Hongo
K
K
Matsui
T
T
Asahara
H
H
Takigawa
M
M
Nishioka
K
K
Kato
T
T
D054392:Adipokines; D000328:Adult; D000368:Aged; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000276:immunology*; D015551:Autoimmunity; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000276:immunology*; D000071451:Chitinase-3-Like Protein 1; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D037102:Lectins; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000276:immunology
D054392:Adipokines; D001323:Autoantibodies; D001324:Autoantigens; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins; D011994:Recombinant Proteins