Monoclonal anti-acetylcholine-receptor antibodies directed against the cholinergic binding site

Abstract

Hybridoma cell lines (32) from mice, rats and chickens reproducing monoclonal antibodies against the acetylcholine receptor from Torpedo californica electric organ were isolated. One of these lines, designated 5.5.G.12, secretes antibodies which are directed against the cholinergic binding site of the acetylcholine receptor. This specific antibody blocked the binding of .alpha.-bungarotoxin to the acetylcholine receptor. The binding of monoclonal antibody 5.5.G.12 to acetylcholine receptor was inhibited by .alpha.-neurotoxins and by other cholinergic ligands in accordance with their affinities to the nicotinic acetylcholine receptor. None of the other monoclonal antibodies obtained inhibited the binding of .alpha.-bungarotoxin to acetylcholine receptor, nor was their binding to the acetylcholine receptor inhibited by cholinergic ligands. The monoclonal antibody elicited against the binding site of Torpedo acetylcholine receptor bound to acetylcholine receptors of various species and organs, demonstrating the wide structural homology between the cholinergic sites of various acetylcholine receptors.