| Abstract: | By using the hybridoma technology, a monoclonal human thyroid cell line was obtained by fusing fresh normal human thyroid cells with a human lymphoblastoid cell line. The resultant cell line, called GEJ, has been selected for its expression of thyrotropin (TSH) receptors and has morphological and functional characteristics of normal human thyroid cells. In the presence or absence of human TSH, the GEJ cell line accumulates iodide, produces thyroid hormones, expresses thyroid membrane antigens, and binds approximately equal to 600 molecules of TSH per cell. The binding site for TSH has all the characteristics of specific receptor (i.e., temperature and time dependencies, dissociation of bound TSH only by high amounts of TSH, and a glycoprotein nature). Scatchard analysis described a curvilinear graph with two dissociation constants (Kd = 0.12 X 10(-9) M and 1.6 X 10(-9) M) with, respectively, 1.2 X 10(3) and 7.2 X 10(3) binding sites per cell. This human thyroid cell line that expresses TSH receptors could be a useful tool for the study of human thyroid disorders. |
