Thyrotropin receptor and leukocyte adhesion molecules in autoimmune thyroid disease: a study of their gene expression by Northern blot analysis and in situ hybridization

Abstract

In order to characterize the role of leukocyte-activating antigens and other immunological parameters in autoimmune thyroid disease, mRNA levels of intercellular adhesion molecule 1 (ICAM-1), endothelial leukocyte adhesion molecule 1 (ELAM-1, E-selectin), invariant chain (Ii) and the thymic hormone thymosin beta (T beta 4) were investigated in 18 human thyroid glands, including eight Graves' thyroids, two Hashimoto's thyroids, two endemic goiters and six healthy controls. Northern blot analysis showed that in autoimmune thyroid disease, expression of ICAM-1 and T beta 4 was correlated to transcript levels of Ii, whereas in the healthy controls, expression of T beta 4, ICAM-1 and ELAM-1 was low or nearly absent. ELAM-1 and TSH receptor (TSH-R) expression, the latter serving as a thyroid specific marker, was increased in some diseased gland but showed no relation to the immunological parameters mentioned above. Localization of the specific mRNAs by in situ hybridization demonstrated a cell-specific expression of TSH-R (thyrocytes), ELAM-1 (vascular endothelial cells) and T beta 4 (cells of hematopoietic origin). In contrast, transcripts of Ii and ICAM-1 were found in thyrocytes, leukocytes and endothelial cells. Our results implicate a coordinate expression of ICAM-1, T beta 4 and Ii in autoimmune thyroid disease, yielding distinct cellular expression patterns. Differential expression of ICAM-1, Ii and the TSH-R in thyroid epithelial cells indicates active regulatory events within the thyrocyte.