[Current protease-antibody-based serodiagnostic tools and their use in the diagnosis of autoimmune thyroid diseases].

The purpose of the investigation was to comparatively study the possible clinicodiagnostic and clinicoprognostic value of thyroglobulin (TG) autoantibodies (anti-TG autoAB) and thyroid peroxidase (TPO) (anti-TPO autoAB) with proteolytic activity (protease-AB) and to develop additional clinicoimmunological criteria for working out a protease-AB-based laboratory serodiagnosis protocol. Sera from 240 patients with autoimmune thyroiditis (AIT), 124 with diffuse toxic goiter (DTG), and 172 with other thyroid diseases were studied. Serum from 40 clinically healthy donors served as a control. Sera were screened for anti-TG and anti-TPO autoAB by enzyme immunoassay and/or radioimmunoassay. Nonspecific proteolytic activity was determined, by incubating a highly purified AB IgG-isotype solution with nonspecific substrate (such as BSA-FITS or thyoredoxine/Trx), followed by the measurement of relative fluorescence shifts at a wavelength of 470 nm. The blood samples taken from patients with AIT or DTG and the highly purified anti-TG or anti-TRO autoAB of IgG isotype were incubated with appropriate human substrates to determine AG-specific proteolytic activity. Proteolysis products were detected by PAAG electrophoresis. An association was found between the rise in the frequency of protease AB, their catalytic activity, a tendency toward autoAB between themselves, and the degree of thyroid tissue degradation in AIT and DTG; some specific features of a serological pattern were noted in diferent dorms of AIT and DTG. For example, the prevailing autoABs have been shown to be TG-specific in AIT and TPO-specific proteases in DTG; also, the detectable catalytic activity of both autoAB in AIT is an order of magnitude higher than that in DTG. No protease ABs have been recorded in other forms of thyroid diseases in which antithyroid autoABs are also frequently detected. The screening procedure for protease AB may be considered as a highly sensitive and specific indicator test in the diagnosis and prediction of AIT and DTG, which allows one to diagnose not only within the framework of major thyroid nosological entities, but much broader, by covering a great variety of syndromal forms of pathology.

[Antithyroid antibodies of varying specificity in the pathogenesis and diagnosis of autoimmune thyroid diseases].

AIM: To compare the possible pathogenetic and clinicodiagnostic value of antithyroid autoantibodies (autoAB) different in specificity, such as monospecific ones to thyroglobulin and thyroid peroxidase (anti-TG and anti-TPO autoAB) and bispecific ones to thyroglobulin and thyroid peroxidase simultaneously (anti-TGPO autoAB), in patients with autoimmune thyroid diseases. MATERIALS AND METHODS: The sera from 240 patients with autoimmune thyroiditis (AIT) and from 124 with diffuse toxic goiter (DTG) were examined. The sera from 40 healthy donors served as a control. The sera were screened for anti-TG and anti-TPO autoAB, anti-TGPO autoAB, by employing enzyme immunoassay and/or radioimmunoassay. The results were statistically processed using the variation statistics-based programs. RESULTS: The specific features of an autoantigenic component to thyroid tissues were found in the sera of patients with AIT and DTG. An association was established between the progression of disease and the phasic change of autoAB populations or their combinations. CONCLUSION: The procedure for evaluating seropositivity for antithyroid autoAB, which is referred to as non-invasive studies, can be considered as a criterion test in the diagnosis and prediction of the course of AIT and DTG.