Comparison of immunofluorescence and immunoperoxidase for demonstration of antinuclear antibodies on HEp-2 substrate.

A comparison of antinuclear antibody (ANA) detection on HEp-2 cell substrate, using immunofluorescence (IF) and immunoperoxidase (IP) techniques, was performed on 183 sera from 178 individuals, with and without connective tissue diseases. All sera were number coded and scored blindly by two independent observers. ANA was detected in 61% of sera by IF and 62% of sera by IP. Positive and negative results corresponded between the two techniques in 97% of sera. Patterns and titres corresponded in 85% of positive sera. The two independent observers scored ANA more consistently with IP than with IF. Both methods were technically simple to perform and produced consistent results with control sera. These data show that IP provides results equivalent to the traditional IF technique for demonstrating ANA on HEp-2 substrate. Fewer discordant results between two independent observers using IP suggests that this technique has technical advantages for interpretation of ANA on HEp-2 substrate.