A UNIQUE TECHNOLOGY FOR THE SEROLOGICAL DIAGNOSTICS OF ANTI-DFS70 ANTIBODIES
- Mandy Sowa, Germany
Abstract
Background and Aims
The immunofluorescence assay is the gold standard for the screening of antinuclear antibodies (ANA) for the serological diagnosis of systemic autoimmune rheumatic diseases (SARD). In this context, the diagnostic value of anti-lens epithelium-derived growth factor antibodies also referred to as anti-dense fine speckled 70 antibodies (anti-DFS70) due to the corresponding dense fine speckled pattern in ANA fluorescence test has been discussed recently. Anti-DFS70 appear to have the potential to discriminate SARD from non-SARD patients. Monospecific anti-DFS70 are characteristic for non-SARD patients whereas the occurrence or concurrence of other ANA is typical for SARD. The CytoBead technology offers a unique opportunity to simultaneously analyze ANA and anti-DFS70.
Methods
One hundred human sera (50 healthy blood donors [BD], 50 anti-DFS-70 positives, pre-characterized with chemiluminescence immunoassay [CLIA]) were tested in the CytoBead ANA+anti-DFS70 assay. Results were compared to data obtained by line immunoassay (LIA; ANA 18 LINE).
Results
The method comparison showed a very good agreement between CytoBead ANA+anti-DFS70 and LIA, CytoBead ANA+anti-DFS70 and CLIA as well as LIA and CLIA (Cohen’s kappa 0.953, 0.976, 0.959, respectively). Furthermore, the fluorescent ANA pattern on HEp-2 cells showed very good agreement with the specific anti-DFS70 [Cohen’s kappa 0.952]. Five out of 50 sera tested anti-DFS70 positive with CLIA showed multiple dots or cytoplasmic mixed ANA patterns. These findings were confirmed with LIA.
Conclusions
The novel CytoBead ANA+anti-DFS70 assay enables the simultaneous analysis of ANA and anti-DFS70 in human sera. This can increase the specificity of ANA screening by immunofluorescence test.