Anti-alprenolol antibodies in the rabbit. A new probe for the study of beta-adrenergic receptor interaction.

We immunized rabbits with an antigen prepared by covalent linkage of alprenolol, a beta-adrenergic receptor antagonist, to bovine serum albumin. Competitive inhibition of [3H]dihydroalprenolol binding to antisera with a variety of unlabeled ligands revealed broad antibody specificity for beta-adrenergic antagonists and agonists. The antiserum was subjected to affintiy fractionation on hydroxybenzylpindolol-Sepharose 4B. Successive elution with 100 mM Tris HCl, 1M NaCl, 4 M LiBr, and 5 M guanidine yielded fractions with increasing affintiy for hydroxybenzylpindolol. The ligand-binding properties of these affinity-fractionated antibodies suggest that certain of these fractions recognize structural aspects of individual beta-adrenergic ligands which are irrelevant to their biological activity, whereas others can be used to distinguish shared functional properties, such as the ethanolamine side chain, within the structural heterogeneity of beta-adrenergic drugs. In particular, elution of hydroxybenzylpindolol-adsorbed antibody with (-)-propranolol allowed identification of an antibody fraction specific for the (-)-stereoisomer. Thus, affinity fractionation of antibodies raised against beta-adrenergic ligands can provide useful analogues for the further study of the recognition properties of the beta-adrenergic receptor.