AN IMMUNOHISTOCHEMICAL STUDY OF NA+ I- SYMPORTER IN HUMAN THYROID TISSUES AND SALIVARY-GLAND TISSUES/

The human Na+/I- symporter (hNIS) is the plasma membrane protein that mediates active iodide uptake into several tissues, such as the thyroi d and salivary glands. To study the distribution and cellular localiza tion of the hNIS protein, we have generated a polyclonal antibody that could detect the hNIS protein by immunohistochemical staining on tiss ue sections. In normal thyroids, hNIS expression is heterogeneous, and it is only detected in sporadic thyrocytes of a given follicle. The h NIS protein was not detected in thyroid carcinomas, yet it was detecte d in the majority of thyrocytes in Graves' thyroids. In salivary gland s, hNIS protein was not detected in acinar cells, but it was detected in ductal cells. The hNIS proteins are clustered in the basal and late ral membranes in cells stained positive for hNIS.