Influence of various factors on glucocorticoid receptors of bronchoalveolar lavage (BAL) cells from rabbits

Abstract

It is supposed that the effects of glucocorticoid on target cells are mediated by glucocorticoid receptors. Recent investigations have demonstrated that changes in the composition and function of immune cells in bronchoalveolar lavage (BAL) cells of patients with immunological lung diseases are associated with the intensity of alveolar septal inflammation, or indicate steroid responsiveness. In order to clarify the physiologic changes of glucocorticoid receptor (GR) we measured the GR content of BAL cells obtained from rabbits with various conditions of the host (aging, immunological activation, malnutrition and pretreatment with prednisolone). The specific binding to GR was carried out by incubating BAL cells with 1, 2, 4, 10, 20, 40 nM 3H-prednisolone in the presence or absence of 1.0 x 10(-6) M unlabeled prednisolone. BAL cells from rabbits of various ages exhibited age-dependent reduction of GR content. There were striking differences of GR content in BAL cells from normal and BCG-vaccinated rabbits. The former yielded 3124 +/- 365 binding sites per cell, whereas activated BAL cells showed considerably higher values (6807 +/- 766). Chronological changes in GR content in BAL cells were also observed in normal rabbits pretreated with intravenous injection of prednisolone (2 mg/kg). The GR content was lowest at 3 hours after administration, reaching a peak at two days and then returned to control level. As for nutritional modulation, GR content tended to increase in the initial phase of fasting (days 4 to 8), and then decreased after day 12. In contrast, there were no significant changes in dissociation constants among BAL cells from animals in normal, immunologically activated and malnourished conditions.(ABSTRACT TRUNCATED AT 250 WORDS)