The Journal of clinical endocrinology and metabolism
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J. Clin. Endocrinol. Metab. · Apr 1985
Specific growth hormone receptors on human peripheral mononuclear cells: reexpression, identification, and characterization.
Although specific GH receptors have been demonstrated in various tissues of a number of species, the presence of GH receptors on human peripheral mononuclear cells (PMC) is controversial. Binding of human GH (hGH) to its receptor as the hypothesized initial step of hormone action was consequently studied using mononuclear cells from peripheral venous blood of normal subjects. Specific binding of [125I]hGH was rapid, reversible, and time and temperature dependent. ⋯ Scatchard analysis of [125I]hGH binding to PMC revealed a receptor with a mean affinity constant of 1.5 +/- 0.2 (+/- SD) X 10(9)/M-1 (n = 72) and a maximal binding capacity of 7.1 +/- 2.0 X 10(-11) M/10(6) cells. The concentrations of calcium, sodium, and magnesium ions in the incubation medium strongly influenced GH binding, whereas pH or potassium concentration did not. As interassay variation of the binding assay was low (14% for total binding; 6% for specific hGH binding), this direct approach to study tissue receptors for hGH in a human in vitro test was reproducible and should encourage the investigation of receptor regulation as well as the study of binding in human disease.