Abstract
Glucocorticoid receptors were measured from leukemic cells of five patients with hairyβcell leukemia as well as a cell line (JOKβ1) derived from one of the patients studied and grown in continuous culture in vitro. Receptor analyses were accomplished using a wholeβcell binding assay with [^3^H]dexamethasone as the ligand. Glucocorticoid receptor sites in the leukemic hairy cells ranged from 5,710 to 11,400 sites/cell, and the mean dissociation constant (K~D~) between the receptor sites and [^3^H]dexamethasone was 0.67Β±0.03 Γ 10^β8^ M. The glucocorticoid receptor nature of the binding activity was verified by demonstration of an appropriate order of competing ability for a selected group of ligands. The cell line JOKβ1 contained 9830 receptor sites/cell with a K~D~ of 0.78 Γ 10^β8^ M. The in vitro growth pattern of this cell line was characterized by an almost complete insensitivity to glucocorticoids. We conclude that the postulated general presence of glucocorticoid receptors in various types of normal and malignant leukocytes extends to hairyβcell leukemia, a disease often characterized by resistance to antileukemic drugs, including corticosteroids. The sole presence of the glucocorticoid receptor thus does not seem to signify steroid responsiveness.