A comparison of indirect immunofluorescence and the avidin-biotin-peroxidase conjugate technic (ABC) in the performance of the antinuclear antibody test.

Antinuclear antibody tests were performed on 19 patients using both the indirect immunofluorescence procedure (FANA) and the avidin-biotin conjugated immunoperoxidase technic (ABC) on HEp-2 cells. Pearson r between the two tests was 0.73. Identical patterns were seen in only 53% of cases, due partially to the chromogen used and partially to positive staining with the ABC method in the face of negative results using the FANA. Reasons are presented to suggest that the ABC method is capable of detecting low-level autoantibodies. Because of the discrepancies seen, the ABC method is currently not recommended as a substitute for the FANA in a clinical setting.