RESUMO
BACKGROUND: Multiplex bead assays, also known as addressable laser bead immunoassays (ALBIA) or Luminex® technology, have provided an alternative to enzyme-linked immunoassay, which is still the most widely utilized routine immunoassay for detection of specific autoantibodies. Our laboratory adopted the ALBIA technology early into its routine service. METHODS: We report the performance and utility of measurement of three different autoantibody types tested using the FIDIS (BMD, Marne La Vallee, France) ALBIA system. The analytes discussed are thyroid antibodies (thyroglobulin [TG], thyroid peroxidase [TPO]), anti-neutrophil cytoplasmic antibodies (ANCA), and ribonucleo-protein (RNP) antibodies. RESULTS: In single antibody analysis, TPO antibody testing was superior to TG antibody in identifying patients with Graves' disease and Hashimoto's thyroiditis. However, testing only TPO antibody would result in missing 8.6% of Graves' and 11.9% of Hashimoto's thyroiditis patients, hence demonstrating an advantage for the multiplex TG plus TPO assay. With respect to ANCA, the FIDIS ALBIA produced an overall similar level of performance to our comparator method, the Phadia fluorescent enzyme linked immunoassay. Sensitivity of the ALBIA for RNP antibodies was low in comparison to countercurrent immunoelectrophoresis, but performance was improved by altering the cutoff value for the assay. CONCLUSIONS: ALBIA technology has many potential advantages in the routine laboratory, but as with any new assay, evaluation must be thorough and ongoing to ensure satisfactory clinical performance is obtained. Both false positive and false negative results have been reported in ALBIA studies. It may be necessary to re-evaluate assay performance and cutoff and consider further clinical correlation.
