Immunoglobulins in myasthenia gravis: effect of human lymph IgG 3 and F (ab')2 fragments on a cholinergic receptor preparation from Torpedo marmorata.

Lymph IgG from patients with myasthenia gravis was shown to inhibit the binding of radio-labelled Naja naja siamensis alpha-neurotoxin to membrane fragments from the electric organ of Torpedo marmorata. This effect could be related to IgG subclass 3 and to the F(ab')2 fragment. These findings confirm the involvement of antibodies of postsynaptic structures in myasthenia gravis.