Comparison of New and Conventional Assay Techniques for Measuring Thyroid Microsomal Antibodies

The determination of microsomal antibodies (MAb) has a long tradition in the diagnosis of thyroid autoimmune disease [1]. The antigen, however, against which those antibodies are directed has only recently been identified and appears to be closely related to or identical with thyroid peroxidase (TPO) [2–5]. These advances in defining the microsomal antigen offer a chance to develop new assay techniques for measuring MAb. Hence, new assays rely on the use of molecularly well-defined antigens instead of crude microsomal fractions being employed in current routine assays for MAb. In the present study we were interested from a clinical point of view to investigate the interaction of MAb with microsomal antigen by three different techniques: (a) a conventional hemagglutination test (HAT), which measures MAb reaction with a crude thyroid microsomal preparation; (b) Western blot analysis, which shows the reaction of MAb with distinct microsomal proteins; and (c) anti-TPO radioimmunoassay, which determines the reaction of MAb with purified human TPO.