Down-Regulation of Glucocorticoid and β-Adrenergic Receptors on Lectin-Stimulated Splenocytes 1

Abstract

Activation of porcine splenocytes with the mitogen, concanavalin A, increases the number of glucocorticoid and β-adrenergic receptors with no change in the apparent dissociation constant. Incubation of splenocytes with concanavalin A in the presence of hydrocortisone 21-sodium succinate prevented this mitogen-induced increase in glucocorticoid receptors. Isoproterenol also prevented the concanavalin A-induced increase in β-adrenoceptors at 24 hr and reduced the binding affinity of these receptors at 48 hr. Neither agonist had any significant effect on the receptor number or binding affinity of nonstimulated cells. These data demonstrate that the increase in the number of glucocorticoid and β-adrenergic receptors that occur on lymphoid cells after activation by a T-cell mitogen can be prevented by appropriate hormone agonists. Down-regulation of receptor number by appropriate agonists appears to be a common regulatory system that is shared by both the neuroendocrine and the immune systems.