Indirect immunofluorescent antinuclear antibody tests: comparison of sensitivity and specificity of different substrates.

Abstract

The sensitivity of the indirect immunofluorescent test for antinuclear antibody varied with the type of substrate used, with fixative procedures employed with these substrates, and with the types of antinuclear antibody present in a given serum. Sera from different patients with systemic lupus erythematosus when screened at a dilution of 1:4 with the indirect immunofluorescent antinuclear antibody test using acetone-fixed rat kidney produced various patterns of nuclear fluorescence. Rat kidney, human leukocytes, and chick erythrocyte nuclei were equally sensitive in the detection of antinuclear activity in patient sera producing homogeneous or rim and fibrillar patterns of fluorescence. Rat kidney and human leukocytes were equally sensitive in detecting antinuclear activity in sera producing speckled patterns of fluorescence. Chick erythrocyte nuclei, however, were relatively insensitive to nonsensitive in detecting antinuclear activity in sera producing patterns of the speckled type. The use of rat kidney sections not fixed in acetone either reduced the sensitivity or rendered the fluorescent test nonsensitive to sera producing speckled patterns of fluorescence on fixed kidney sections.