A comparative study of glucose oxidase versus FITC-labeled antibody techniques for the detection of antinuclear...

Sera from 98 patients were examined for antinuclear antibodies (ANA). The patient population has been previously identified clinically as having the following diseases: systemic lupus erythematosus, scleroderma, dermato or polymyositis, discoid lupus, rheumatoid arthritis, Raynaud phenomena only, undifferentiated connective tissue disease, and psoriasis. All sera samples were tested using both HEp-2 cells and rat kidney tissue as substrates and were stained with both fluorescein-conjugated antihuman antibody and glucose oxidase-conjugated antibody to human IgG. Each serum was initially tested at a screening dilution of 1:40 with PBS. Positive sera were serially diluted until an end point was observed. The number of dilutions for each specimen in all four combinations was compared mathematically using the Pearson product moment correlation. Using this method, glucose oxidase- and fluorescein-conjugated antinuclear antibody (FANA) techniques appear to have a high positive correlation (r = 0.92 kidney, r = 0.95 Hep-2) in this patient population. In our experience, the glucose oxidase technique offers comparable results to FANA and is ideally suited for the hospital laboratory, especially facilities without the benefit of a fluorescent microscope.