Expression and function of a CD3-like molecule on normal and abnormal human parathyroid cells.

Abstract

Normal and abnormal human parathyroid tissue express the T-lymphocyte protein CD4, and parathyroid and lymphocyte cells show similarities with respect to mechanisms of calcium permeability and regulation of the cytoplasmic calcium concentration. Anti-Leu4, a monoclonal antibody recognizing the T-lymphocyte glycoprotein complex CD3, is used to immunohistochemically stain normal and abnormal human parathyroid cells and to explore influences on the parathyroid hormone (PTH) secretion of enzymatically dispersed parathyroid cells. Parathyroid glands of patients with different forms of hyperparathyroidism displayed variable expression of the anti-CD3 reactive complex. The stainings correlated both positively and inversely to immunoreactivity for a previously defined calcium sensor, the decreased expression of which may constitute a molecular basis for hyperparathyroidism. Incubation of parathyroid cells with the anti-Leu4 antibody inhibited PTH secretion and reduced its sensitivity to external calcium without influence on parathyroid cytoplasmic calcium concentration. The results suggest that the human parathyroid cells express a CD3-like molecule with the ability to interact in PTH release.