SPECTROTYPIC ANALYSIS OF ANTIBODIES TO ACETYLCHOLINE-RECEPTORS IN EXPERIMENTAL AUTOIMMUNE MYASTHENIA-GRAVIS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 57  (1) , 41-50
Abstract
The isoelectric focusing pattern of antibodies expressed in rats with experimental autoimmune myasthenia gravis (EAMG) induced by immunization with acetylcholine receptors (AChR) purified from Torpedo californica. Sera or tissue eluates were obtained at intervals in the course of disease and subjected to isoelectric focusing. The focused antibodies were detected by autoradiography of gels labeled with 125I-.alpha.-bungarotoxin conjugated AChR. Reverse electrofocusing was used to separate complexes of antibody and AChR formed in vivo, thereby allowing detection of the full spectrotype (banding pattern). As little as 1.1 .times. 10-12 mol of monoclonal antibodies (MoAb) to AChR yielded distinct bands of radiolabeled antigen binding by this technique. The anti-AChR MoAb studied showed a multitude of bands localized in neutral to alkaline position. The clonotypes expressed in late post-immunization sera were compared to early sera. The spectrotypes of immunized Lewis and Brown Norway rats were not identical. In early sera most of the isoelectric focusing bands were specific for T. californica AChR, whereas in late sera further expansion of the repertoire produced bands that reacted with rat muscle AChR as well. The focused bands that bound rat AChR also bound T. california AChR. The anti-AChR antibodies eluted from muscles of rats with EAMG showed similar binding patterns to anti-receptor antibodies in rats'' sera. The antibody specificities detected in serum are the same specificities which are effective in binding to muscle AChR in vivo. Minor specificities of serum anti-receptor antibodies are not disproportionately represented in the antibodies actually bound at the neuromuscular junction in EAMG.