Prevalence and Clinical Significance of Anti-DFS70 in Antinuclear Antibody (ANA)–positive Patients Undergoing Routine ANA Testing in a New Zealand Public Hospital

To the Editor: The term antinuclear antibodies (ANA) originally referred to autoantibodies directed against nuclear antigens and antigens in the cell cytoplasm or membrane1. The presence of elevated ANA is considered as the hallmark diagnostic test for systemic autoimmune rheumatic diseases (SARD). In most New Zealand (NZ) laboratories, ANA are detected by indirect immunofluorescence test (IIF) on HEp-2. However, fluorescent patterns are sometimes difficult to interpret2,3. Recent advances in autoimmune technologies have emerged for ANA testing, and laboratories in NZ are moving into acquiring the required knowledge and skills. In our laboratory, ANA screening slides are interpreted by a NOVA View automated IIF slide reader (INOVA Diagnostics Inc.), which incorporates a digital analysis image system, pattern recognition algorithms, and preset cutoff values. Problems still exist for the laboratory community to determine whether this system efficiently identifies antigens of clinical significance and whether the different automated systems have an appropriate level of pattern recognition agreement4. The extractable nuclear antigen (ENA) panel is a test performed as … Address correspondence to Dr. F. Merien, Auckland University of Technology, School of Science, 34 St Paul St., Auckland 1142, New Zealand. E-mail: fmerien{at}aut.ac.nz