Production of antibodies to alpha(181-192) peptides of neuronal nicotinic acetylcholine receptor coupled to protein carriers in different orientations.

The antibodies to nicotinic acetylcholine receptor alpha(181-192) synthetic peptides were elicited in rabbits and mice using the peptides conjugated to protein carriers in different orientations, either through C-terminal Cys (S-conjugates), or through amino groups (N-conjugates). S-conjugated peptides were less potent in eliciting peptide-specific antibodies compared to N-conjugates and this type of conjugation resulted in antibodies to the coupling reagent. However, the epitopes present in either S- or N-conjugated peptides appeared to be similar, indicating that amino acid residues, which form the epitope, were located in the middle part of the peptide and did not include both N- and C-terminal residues.

Structure of epitopes recognized by the antibodies to alpha(181-192) peptides of neuronal nicotinic acetylcholine receptors: extrapolation to the structure of acetylcholine-binding domain.

Using the alpha(181-192) peptides of neuronal nicotinic acetylcholine receptor (nAChR) and Ala-substituted peptide analogues, amino acid residues critical for specific monoclonal antibody (mAb) binding were identified. By means of 2D nuclear magnetic resonance (2D-NMR) analysis followed by molecular modeling, it was found that mAb binding resulted in stabilization of the free alpha3(181-192) peptide flexible conformation yielding an extended structure with residues 6-11 of the peptide being in direct contact with the Ab. Since the Ab binds the native AChR as well, it is suggested that the corresponding fragment of AChR alpha3 subunit is exposed to solution and also appears in extended conformation.

Epidemiology of seropositive myasthenia gravis in Greece.

Objectives: To study the epidemiological characteristics of myasthenia gravis in Greece.

Methods: A population based study was carried out of seropositive myasthenia gravis in Greece for the period from 1 January 1983 to 30 June 1997; 843 patients were studied.

Results: The average annual incidence for the period 1992-7, for which the database is complete, was 7.

Anti-neuronal nicotinic receptor antibodies in MG patients with thymoma.

We tested 24 MG patients with thymoma (11 invasive) for the presence of anti-neuronal nicotinic receptor subtype antibodies and found that none had antibodies against the alpha 7-containing subtype, and only one (with invasive thymoma) had antibodies directed against the alpha 3-containing subtype. In this patient, the anti-alpha 3 antibodies recognized the extracellular part of the alpha 3 subunit. They developed later than the anti-alpha 1 muscle antibodies, with their titer increasing during the illness, while that of the anti-alpha1 muscle antibody decreased.

Reconstitution of conformationally dependent epitopes on the N-terminal extracellular domain of the human muscle acetylcholine receptor alpha subunit expressed in Escherichia coli: implications for myasthenia gravis therapeutic approaches.

Myasthenia gravis (MG) is an autoimmune disease, caused by autoantibodies against the muscle acetylcholine receptor (AChR), an oligomeric transmembrane glycoprotein composed of alpha(2)beta gamma delta subunits. The alpha subunit carries in its N-terminal extracellular domain the main immunogenic region (MIR), a group of conformationally dependent epitopes that seems to be a major target for the anti-AChR antibodies in MG patients. Detailed epitope studies on pathogenic anti-AChR antibodies have been hindered because the binding of most of these antibodies is conformationally dependent, which precludes the use of denatured AChR fragments.