NEW YORK (Reuters Health) - Assay of anti-calpastatin autoantibodies appears to be particularly helpful in diagnosis of rheumatoid arthritis (RA), according to Japanese researchers. As lead investigator Dr. Sachiko Iwaki-Egawa told Reuters Health, “the sensitivity and specificity of anti-calpastatin are higher than those of rheumatoid factor and are equal to those of anti-cyclic citrullinated peptide (anti-CCP).”
Dr. Iwaki-Egawa of Hokkaido College of Pharmacy, Otaru and colleagues note that calpains can degrade cartilage proteoglycan and can be inhibited by calpastatin.
Anti-calpastatin autoantibodies have been identified in the sera of patients with RA and the investigators sought to determine whether an assay for their presence might be of diagnostic value.
Using human erythrocyte calpastatin as an antigen, the researchers tested sera from patients with a variety of autoimmune diseases for evidence of anti-calpastatin autoantibodies.
IgG antibodies were found in 48 of 58 RA patients (82.8%) but only in 2 of 11 patients with osteoarthritis (8.3%). Corresponding proportions in other conditions ranged from none in systemic sclerosis to 20% in those with Sjogren’s syndrome.
The IgG antibodies had a 96.1% specificity for RA and almost 90% of such patients were positive for IgG or IgM anti-calpastatin autoantibodies.
Dr. Iwaki-Egawa noted that further work will be needed to ascertain levels in various stages of RA, but the team concludes that “we have developed a simple, sensitive, specific and quantitative ELISA...that may have a high diagnostic value.”
Source: J Rheumatol 2004;31:17-22. [ Google search on this article ]
Copyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
