Parathyroid histology and cytology with monoclonal antibodies recognizing a calcium sensor of parathyroid cells.

Two monoclonal antibodies reacting with surface structures on exclusively parathyroid cells and proximal kidney tubule cells were evaluated in the microscopic diagnosis of parathyroid disease. Immunostained cryosections of adenomatous and hyperplastic parathyroid glands from 30 hypercalcemic patients with primary or uremic hyperparathroidism (HPT) showed a reduced and heterogeneous staining with the antibodies. This contrasted with the intense and even staining of normal and suppressed human parathyroid glands, as well as lymph node metastases of parathyroid carcinoma. Fine-needle aspiration biopsies and imprints of the parathyroid glands showed a conspicuous antibody staining that enabled the identification of parathyroid cells. The antibodies seem to provide new means for histologic and cytologic identification of normal and pathologic parathyroid tissue, in conjunction with their highly restricted tissue reactivity. Because one of the antibodies interacts with a surface receptor mechanism of the parathyroid cells that is involved in the sensing and gating of calcium and, thereby, also with the regulation of parathyroid hormone release, the unequivocal demonstration of reduced staining of the adenomatous and hyperplastic parathyroid tissue suggests that HPT is associated with reduced expression of the calcium sensoring mechanism of the pathologic parathyroid tissue.