Glucocorticoid receptors in normal human eosinophils: comparison with neutrophils

Saturation analysis with [3H]-dexamethasone was employed to measure glucocorticoid binding in purified preparations of human eosinophils and neutrophils. Eosinophils contained 10.8 +/- 1.3 x 10(3) high-affinity receptor sites per cell, with a dissociation constant (Kd) of 15.3 +/- 0.6 nM dexamethasone. Cortisol was capable of competing with [3H]-dexamethasone in the binding reaction, whereas progesterone, estradiol, estriol, and testosterone were less effective. Saturable glucocorticoid binding in neutrophils had a Kd of 17.7 +/- 0.8 nM dexamethasone with 11.1 +/- 0.8 x 10(3) sites per cell and displayed similar steroid specificity. These data indicate that normal human eosinophils have glucocorticoid receptors with characteristics similar to those in neutrophils and that in these cells ligand-receptor interaction can occur at physiologic glucocorticoid concentrations. Furthermore, these results suggest that certain glucocorticoid effects on eosinophils and neutrophils may be mediated through specific receptors.