Doença tiroideana auto-imune : expressão de colageno IV e laminina e relação com anti-corpos circulantes antimembrana basal

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

The purpose of the present study is to evaluate serological and morphologic aspects concerning the basement membrane (BM) of the thyroid follicle in autoimmune thyroid disease (ATD). In this way, new elements for ~ better understanding of its pathophisiology could be suggested. In order to detect antibodies to collagen IV and laminin, two major components of the BM, serological tests of patients with the diagnosis of different thyroid diseases were performed by the transfer eletrophoresis method followed by immunoblot. Only in the Basedow-Graves disease antibodies, to various collagen IV fractions were detected. Also, antibodies to laminin were found in these patients sera, detected by recognition of the 57 kDa fraction of laminin. These antibodies are probably involved in the pathogenesis of ATD and are not just consequence of hypermetabolic states due to hyperthyroidism, since no antibodies could be detected in thyroid hyperfunction caused by benign thyroid neoplasia. Production of such antibodies could be atributed to or cause BM alterations as a consequence of disturbed immunological tolerance to their components, which are otherwise recognized as self, and induction of immunologic response. If this is true, immunohistochemical staining of collagen IV an Iaminin could be useful in detecting follicIe BM disruption in A TD. Our results do not corroborate this hypothesis, since we were not able to find BM alterations in thyroid diseases, even in areas of heavy lymphoplasmatic inflamation. Finding of focal BM thinning, mainly in Graves disease, could be preliminarly explained by hypermetabolism, delivery of collagen IV and laminin to the circulation and induction of antibody production against them. This hypothesis, however, is not corroborated by the findings in toxicadenoma, another cause of hyperthyroidism, in wich BM thinning is not present. In Hashimoto thyroiditis, in disagreement with previously reported data, no disruption, nor significant BM thinnin g were seen. The pathogenetic role of these antibodies is not yet clear, but it does not seem that they cause follicular BM damage. Further investigations are needed to characterize biologically such antibodies and to understand their relationship to follicular BM in A TD

ASSUNTO(S)

doença de graves membrana basal tiroide autoimune

ACESSO AO ARTIGO

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