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. Our data suggest that there is no correlation between the presence of anti-alpha 3 antibodies and thymoma.