PRESENCE OF ENDOTHELIN-1 IN THE NORMAL AND PATHOLOGICAL HUMAN THYROID

An immunohistochemical study with two rabbit polyclonal antibodies I-A R76 and CA-08-351 against Endothelin-1 (ET-1) was performed in 133 hum an thyroid specimens: 5 normal thyroids, 30 multinodular goiters (15 t oxic and 15 nontoxic), 20 Graves' diseases, 5 Hashimoto's thyroiditis, 26 adenomas (6 Hurthle cell, 16 toxic and 4 nontoxic), 30 classic pap illary carcinomas, 3 minimally invasive follicular carcinomas, 1 widel y invasive follicular carcinoma, 3 undifferentiated carcinomas and 10 medullary carcinoma. All normal thyroids, non toxic multinodular goite rs and non toxic adenomas, 4 (66%) Hurthle cell adenomas, 3 (15%) Grav es' diseases, 1 (33%) case of minimally invasive follicular carcinoma showed rare follicular cells with weak cytoplasmic immunoreactivity. M any immunoreactive follicular cells, with or without oxyphilic changes , were observed in all specimens of Hashimoto's disease, while the lym phocytic infiltrate was always negative. Twenty-seven (90%) classic pa pillary carcinomas were positive. Immunoreactivity was intracytoplasmi c, weak in 14 cases and intense in 13. The cells of toxic adenoma and toxic multinodular goiter were negative, whereas the acellular stroma was intensely posit:ive in both cases. Medullary and undifferentiated carcinomas were negative. These results show ET-1 immunoreactivity in normal and pathological human thyroids. In particular, the high conten t of this peptide in the thyroid papillary carcinoma suggests that ET- 1, whose mitogenic role has recently been emphasized, could be involve d in the growth of this tumor.