The prevalence of antinuclear antibodies in healthy young persons and adults, comparing rat liver tissue sections with HEp-2 cells as antigen substrate.

The prevalence of antinuclear antibodies (ANA) was studied in 290 healthy adults, aged 20-88 years, and in 219 children, aged 1 month to 15 years. Two antigen substrates, rat liver tissue sections and HEp-2 cells, were compared at different serum dilutions. At titre 1/40, the number of positive adult samples was 6.9% with HEp-2 cells and 6.2% with rat liver. Using a lower serum dilution, HEp-2 cells were shown to be significantly more sensitive than rat liver. However, 25% of the positive samples at serum titre > or = 1/40 could only be found on HEp-2 cells, as compared to 17% for rat liver, even after extended investigation. In children, 7.3% of the samples were positive using HEp-2, as compared to 2.3% with rat liver tissue, at titre 1/10. None of the samples were positive for nDNA or other specific antigens as measured by immunodiffusion. One sample had antibodies against core histones and two samples showed antibodies against subcellular antigens by immunoblot. We conclude that the occurrence of ANA in healthy Swedish children and adults is similar to previous studies from other countries. Both rat liver tissue and HEp-2 cells were found to be suitable for screening purposes, if the increased sensitivity of HEp-2 cells is taken into consideration, particularly with regard to children. Furthermore, it may be necessary to use more than one substrate to exclude ANA positivity in clinical practice.