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MR Vol.10 No.1 indexに戻る
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MODERN RHEUMATOLOGY
Vol.10 No.1 |
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Domain reactivity of autoantibodies to calpastatin
in patients with systemic rheumatic diseases |
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| Y. Kanazawa, Y. Kaneshiro, M. Sawa, H. Yasuoka,
T. Nojima, Y. Ohosone, T. Mimori |
| (1)Division of Rheumatology, Department of
Internal Medicine, Keio University School of Medicine, 35 Shinanomachi,
Shinjuku-ku, Tokyo 160-8582, Japan |
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| Abstract |
| Abstract Autoantibodies to calpastatin (endogenous
inhibitor of calpain, a calcium-dependent neutral proteinase) have
been detected in sera of patients with rheumatoid arthritis (RA)
and other diseases. We investigated the epitope reactivity of anticalpastatin
autoantibodies in patients with rheumatic diseases. cDNAs encoding
each calpastatin domain (L, I, II, III, and IV) were amplified by
PCR and ligated into an expression vector. The fusion proteins were
expressed in E. coli. The presence of autoantibodies specific for
each calpastatin domain was assayed in sera of patients with various
rheumatic diseases by immunoblotting the fusion proteins with these
sera. Of the RA patient sera, 81% reacted with at least one calpastatin
domain. This reaction was significantly greater than with sera from
patients with systemic lupus erythematosus (46%), scleroderma (32%),
polymyositis/dermatomyositis (43%), and normal controls (13%). Domains
I and II were recognized by RA patient sera significantly more than
by other patient sera, whereas domains III and IV reacted almost
equally among all patient sera. Although, collectively, sera from
RA and lupus patients reacted equally with all domains, scleroderma
sera tended to react with only domains I and IV and myositis sera
tended to recognize only domains III and IV. Patients with RA positive
for anticalpastatin antibodies exhibited more active disease (i.e.,
a higher erythrocyte sedimentation rate and C-reative protein level)
than antibody-negative patients. Our results suggest that anticalpastatin
antibodies were detected in RA with the highest frequency and that
different domain reactivity was shown among different diseases. The
presence of these antibodies in sera may be related to the type of
disease and, in RA, with disease activity, suggesting their importance
in rheumatic disorders. |
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| Key words |
| Key words Autoantibody ・ Calpastatin ・ Calpain
・ Rheumatoid arthritis ・ Autoimmune disease |
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