EXPRESSION OF TENASCIN IN LYMPHOCYTIC AUTOIMMUNE-THYROIDITIS

Aims-To study the distribution of tenascin by immunocytochemistry in a utoimmune diseases of the thyroid. Methods-Thyroids from patients with inflammatory lesions of the thyroid (lymphocytic thyroiditis Hashimot o, Grave's disease, thyroiditis DeQuervain) were studied by immunocyto chemistry using antibodies against tenascin, collagen III, and collage n IV. Results-In autoimmune lymphocytic thyroiditis Hashimoto there wa s a characteristic corona-like staining pattern of tenascin around all activated lymph follicles with germinal centres. This staining patter n contrasted with the immunoreactions for collagen III and IV, which w ere not enhanced in the perilymphofollicular interstitium. In cases of thyroiditis DeQuervain the areas of early and ongoing fibrosis showed some diffuse staining for tenascin and for collagen III. Enhanced dif fuse immunostaining for collagen IV in the perivascular and interfolli cular interstitium was present in cases of Grave's disease. In Grave's disease no characteristic immunoreaction was detectable for tenascin. Conclusions-The corona-like expression of tenascin around lymphofolli cular infiltrates is distinctive of cases of lymphocytic thyroiditis. A similar staining pattern for tenascin has been reported in lymphoid hyperplasia of the thymus associated with myasthenia gravis, another a utoimmunological disorder. There are good arguments that the activatio n and infiltration of lymph follicles in the thyroid during the course of autoimmune diseases lead to stimulation and activation of the surr ounding mesenchyme producing tenascin as part of the extracellular mat rix.