Comparison of four enzyme immunoassays for the detection of immunoglobulin G antibody against glomerular basement membrane.

Abstract

Goodpasture syndrome is a life-threatening autoimmune kidney and pulmonary disease that is characterized by pulmonary hemorrhage, renal failure, and the presence of autoantibodies against glomerular basement membrane (GBM) by indirect fluorescent antibody (IFA) techniques. In 1988, these antibodies were found to be specific for the noncollagen region of the alpha3 collagen IV chain. The antigen is characterized by a restricted tissue distribution occurring mainly in the kidneys and lungs. Specific enzyme immunoassays (EIAs) for anti-GBM have now been developed for in vitro diagnostic use in the laboratory. Our objective in this study was to compare the results obtained using four different EIAs for detecting anti-GBM IgG antibody with those using the standard IFA method using tissue from human kidney. Thirty-two patients with suspected Goodpasture syndrome, and 10 control sera were included in the study. GBM EIAs were purchased from or donated by the following vendors: Scimedx Corporation (Denville, NJ), INOVA Diagnostics (San Diego, CA), The Binding Site (Birmingham, England), and Wieslab (distributed by DiaSorin, Inc., Stillwater, MN). Percent agreement, sensitivity, and specificity were calculated for each EIA as compared to IFA. The results were as follows: Binding Site: 83.3, 100.0, and 72.0%; Wieslab: 95.2, 94.1, and 96.0%; INOVA: 96.2, 100.0, and 92.3%; and Scimedx: 81.0, 100.0, and 68.0%. We conclude that the INOVA and Wieslab GBM IgG EIAs compared well with the standard GBM IFA method using tissue from human kidney. The Scimedx and Binding Site EIAs had eight and seven false-positive results, respectively, when compared to GBM IFA using human kidney. The authors recommend conducting thorough evaluations of EIAs that screen for anti-GBM antibody before their implementation in the clinical laboratory. We also recommend confirming GBM EIA-positive sera by the standard IFA method using tissue from human kidney.