Characteristics of monoclonal antibodies to denatured Torpedo and to native calf acetylcholine receptors: Species, subunit and region specificity

Abstract

Seventy-five monoclonal antibodies (mAbs) to sodium dodecyl sulfate-denatured Torpedo california (66 mAbs) and intact fetal calf (9 mAbs) acetylcholine receptor (AChR) were produced. These mAbs were characterized for subunit, region and species specificity, for Ig class and subclass, for protein A binding and for antigen-crosslinking capacity. Fourteen were identified as anti-α, 35 were anti-β, 8 were anti-γ and 15 were anti-δ. None of the 11 anti-α derived from denatured AChR bound to the main immunogenic region (MIR) as judged by antibody competition assays. This contrasts with previous results using mAbs against native AChR, the majority of which bind to the MIR. Thirty-eight mAbs crossreacted with some or all of the tested AChRs from electric organs and mammalian muscles in addition to the immunogen. Eight anti-α, 9 anti-β and 1 anti-δ mAbs showed good to excellent autoantibody activity. Analysis by sucrose gradient centrifugation of some AChR-mAb complexes revealed that some mAbs form intermolecular and other form intramolecular crosslinking of the AChR. The described mAbs have proven valuable tools in AChR and myasthenia gravis research.