High diagnostic value of anticalpastatin autoantibodies in rheumatoid arthritis detected by ELISA using human erythrocyte calpastatin as antigen

• Published in: Journal of rheumatology Vol. 31; no. 1; p. 17
• Main Authors: Iwaki-Egawa, Sachiko, Matsuno, Hiroaki, Yudoh, Kazuo, Nakazawa, Fujio, Miyazaki, Kyousuke, Ochiai, Akira, Hirohata, Shunsei, Shimizu, Masatoshi, Watanabe, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Canada 01.01.2004
• Subjects: Adult; Aged; Arthritis, Rheumatoid - diagnosis; Arthritis, Rheumatoid - immunology; Autoantibodies - blood; Autoantigens - immunology; Blotting, Western; Calcium-Binding Proteins - immunology; Enzyme-Linked Immunosorbent Assay - methods; Erythrocytes - immunology; Female; Humans; Immunoglobulin G - blood; Immunoglobulin M - blood; Male; Middle Aged; Osteoarthritis - diagnosis; Osteoarthritis - immunology; Sensitivity and Specificity
• ISSN: 0315-162X; 1499-2752

To develop a quantitative method of measuring autoantibodies against human calpastatin in rheumatoid arthritis (RA) and to determine their diagnostic value compared with other autoimmune and articular diseases. We performed a highly sensitive ELISA for IgG and IgM anticalpastatin autoantibodies in human sera using human erythrocyte calpastatin as an antigen. Samples were diluted 1:2000 for the measurement of IgG and 1:400 for IgM. IgG anticalpastatin antibodies were found in the sera of 48 of 58 patients (82.8%) with RA. In contrast, IgG anticalpastatin antibodies were found in the sera of only 2 of 11 (8.3%) patients with osteoarthritis (OA). Compared to sera from patients with other autoimmune diseases, anticalpastatin antibody sensitivity for RA was better than that of systemic lupus erythematosus (5.6%), systemic sclerosis (0%), mixed connective tissue disease (0%), and Sjögren's syndrome (20%). IgG anticalpastatin antibodies also showed high specificity (96.1%) for RA. Almost 90% of patients with RA were positive for IgG or IgM anticalpastatin antibodies. We have developed a simple, sensitive, specific, and quantitative ELISA for anticalpastatin antibodies that may have a high diagnostic value for RA.