Expression of CD56/N-CAM antigen and some other adhesion molecules in various human endocrine glands

CD56/N-CAM antigen, 140 kDa isoform of neural cell adhesion molecule (N-CAM) has been previously traced by some of us in follicular epithelium of human thyroid by immunohistochemistry. The reaction product was cell membrane bound, being stronger in hyperactive thyroid as compared to colloid goiter. In the current study, CD56 was searched in other endocrine glands and their tumors including parathyroids, adrenal cortex and parafollicular C cells of the thyroid (TT cell line). The antigen was also examined in the tissue extracts of endocrine and nonendocrine organs by dot blot immunoassay and anti CD56 monoclonal antibody. Besides, some other cell adhesion molecules (CAMs) were looked for in the tissues and cells tested. It has been found that CD56 is expressed in all zones of adrenal cortex, albeit in various intensity. The reaction was cell membrane bound in cortical hyperplasia and adenoma but cytoplasmic in the carcinoma of adrenal cortex. Other endocrine tissues and cells tested were devoid of CD56. Presence of CD56 antigen could be confirmed by dot blot assay with 3M KCl and NP40 extracts of both, thyroid and adrenal glands. Apart from CD56 some other CAMs could be traced in thyroid cell membranes including CD44, VLA-3 integrin and E-cadherin, what was not the case in the adrenal cortex. In parathyroids and parathyroid adenoma, diffuse immunostaining of E-cadherin and irregular, focal expression of CD44 was observed. These results show, apart from CD56, abundance of other CAMs in the thyroid gland and their relative scarcity in other endocrine tissues tested.