Anti-alprenolol anti-idiotypic antibodies bind to beta-adrenergic receptors and modulate catecholamine-sensitive adenylate cyclase.

Abstract

Rabbit antibodies induced against alprenolol, a potent .beta.-adrenergic antagonist, bind to other antagonists and to catecholamine agonists. Anti-idiotypic antibodies were raised against the anti-alprenolol Ig. The anti-idiotypic antibodies specifically bind and agglutinate turkey erythrocytes; this is not observed for human or sheep erythrocytes, which are devoid of .beta.-adrenergic receptors. The anti-idiotypic antibodies compete with (-)-[3H]-dihydroalprenolol for binding on the .beta.-adrenergic receptors on purified turkey erythrocyte membranes. The binding to the membrane-bound receptors is prevented by preincubation of the anti-idiotypic antibodies with their immunogen, the antialprenolol. The binding to the receptor is not merely passive: the anti-idiotypic antibodies stimulate basal adenylate cyclase activity [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and enhance adenylate cyclase activation by catecholamine. These observations support the notion that anti-idiotypic antibodies may constitute an internal image of the original antigen and may mimic its biological effects.