ELISA system for detection of immune responses to FVIII: a study of 246 samples and correlation with the Bethesda assay

• Published in: Haemophilia : the official journal of the World Federation of Hemophilia Vol. 13; no. 3; pp. 317 - 322
• Main Authors: SAHUD, M. A., PRATT, K. P., ZHUKOV, O., QU, K., THOMPSON, A. R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2007
• Subjects: acquired haemophilia; alloantibody; anti-haemophilic factor; Autoantibodies - blood; Autoantibodies - immunology; Case-Control Studies; Enzyme-Linked Immunosorbent Assay - methods; Enzyme-Linked Immunosorbent Assay - standards; Factor VIII - immunology; FVIII; FVIII:C inhibitor; Hemophilia A - blood; Hemophilia A - immunology; Humans; Nijmegen Assay
• ISSN: 1351-8216; 1365-2516
• DOI: 10.1111/j.1365-2516.2007.01450.x

Inhibitors of FVIII are usually IgG polyclonal antibodies that develop as alloimmune responses in patients with congenital haemophilia A or as autoimmune responses resulting in acquired haemophilia. Their recognition can be difficult, especially when the titre is low. Furthermore, results from a Bethesda assay often require several days as samples are referred to a specialty laboratory. The aim of this study is to assess the utility of an ELISA system for detecting immune responses to FVIII. A total of 246 plasma samples submitted from 176 individuals with immune responses to FVIII, as verified with the Bethesda assay, and samples from 50 control subjects were tested for the presence of FVIII‐specific IgG using an ELISA‐based assay. Paired sera from 18 of the patients were also tested by the ELISA. Of the 246 samples that were positive for a FVIII inhibitor by the Bethesda assay, 235 (95.5%) were also positive by ELISA. The regression coefficient, using Log BU was r = 0.82. The correlation data were strengthened when 27 inhibitor samples were diluted further. There was a strong correlation between ELISA results for the 18‐paired serum and plasma samples (r = 0.99). There is a strong correlation between the ELISA and Bethesda methods in detecting immune responses to FVIII. The ELISA provides rapid screening that could be available well in advance of confirmation by the Bethesda assay.