Glucocorticoid receptors in human polymorphonuclear and mononuclear leucocytes. Concentrations and binding...

Both polymorphonuclear (PMN) and mononuclear (MN) leucocytes constitute targets for glucocorticoid hormones. In order to comparatively characterize the earliest steps of steroid action in these cell populations, we investigated the concentrations and specificities of glucocorticoid receptors in purified human PMNs and MNs by a whole-cell binding assay using (3H)dexamethasone as the ligand. PMNs and MNs were found to contain the same amounts of glucocorticoid receptors (4720 and 4900 receptor sites/cell, respectively). The equilibrium dissociation constant (KD) of the interaction between the cellular receptor and (3H)dexamethasone was about the same (1 x 10(-8)M) in both cell populations. No significant difference in the specificities of the steroid binding sites in PMNs and MNs were found; competition studies revealed the following order of relative binding affinities for a number of compounds: betamethasone greater than dexamethasone greater than prednisolone greater than cortisol greater than deoxycorticosterone = progesterone greater than aldosterone greater than testosterone greater than estradiol-17 beta. We conclude that known differences in the sensitivities of PMNs and MNs to glucocorticoids are apparently not caused by differences in the concentrations or characteristics of their glucocorticoid receptors.