Antibodies to brain proteins in a patient with subacute cerebellar degeneration and Lambert-Eaton myasthenic syndrome.

The serum IgG of a 50-year-old woman with lung cancer associated with subacute cerebellar degeneration and Lambert-Eaton myasthenic syndrome showed the antibody activity to rat brain proteins. Using an immunoblotting method, the patient serum reacted with 98 kDa neutral cytoplasmic protein and 68 kDa membrane protein. These proteins were different in molecular weight from those we described previously (Tanaka et al. 1986), which suggests that proteins reacting with serum antibody are variable individually among patients with subacute cerebellar degeneration. These proteins from human brain could not be stained by the patient's serum IgG since these antigen proteins needed to be prepared quickly after death under protease inhibitors and were thought to be easily degraded.