A CD4-like molecule can be expressed in vivo in human parathyroid

The expression of several epitopes of CD4, a molecule usually restricted to a subset of T-lymphocytes, was observed after immunofluorescent labeling of frozen-cut sections of human parathyroid. Seven samples obtained from three subjects presenting adenomas and from seven renal insufficiency patients with secondary or tertiary hyperplasia were found to express this molecule. Dot enzyme-linked immunosorbent assay, polyacrylamide gel electrophoresis, and Western blotting were used to characterize this peptide in cytosol and membrane fractions of these glands. These studies confirmed, in the parathyroids found positive in immunofluorescence, the presence of a protein with a mol wt similar to that of lymphocyte-derived CD4.