Detection of anti-nuclear antibodies from patients with systemic rheumatic diseases by ELISA using HEp-2 cell nuclei

A microtiter plate was coated with cell nuclei from HEp-2 cells, and the stabilized nuclei were fixed with acetone for an enzyme-linked immunosorbent assay (ELISA). Autoantibodies against nuclear antigens were detected from the sera of patients with various systemic rheumatic disease but not from healthy individuals by means of the nucleus ELISA procedure. Ninety-one percent of antinuclear antibody (ANA)-positive sera as demonstrated by immunofluorescence (IF) test were also judged as positive for ANAs by the nucleus ELISA and 5% of them as pseudo-positive. Patient's sera with homogeneous and fine-speckled IF patterns displayed the highest ELISA titers. A large portion of ss-A/Ro antigen is localized in the cytoplasm; therefore, anti-ss-A/Ro antibody was hardly detected by nucleus ELISA. The population of ANAs detectable by nucleus ELISA included anti-ss-B/La, anti-DNA, anti-histone, anti-Sm, anti-RNP, and anti-scl-70.