Paraneoplastic encephalo-myelo-ganglionitis: cellular binding sites of the antineuronal antibody.

The cellular binding sites of an antineuronal antibody were characterized in an autopsy case of the paraneoplastic encephalo-myelo-ganglionitis. A 61 year-old woman developed a subacute sensorimotor polyneuropathy and, later, multiple involvement of cranial nerves, disturbance of consciousness, and generalized seizure. An autopsy revealed a small cell lung carcinoma and neuropathological changes that included disseminated encephalitis, spinal anterior horn lesions, severe loss of dorsal root ganglion neurons, and secondary degeneration and loss of the nerve fibers in the spinal posterior column and peripheral nerves. The serum IgG from the patient contained antineuronal antibody(s) including an antibody to 35- to 37-kDa neuronal antigens called anti-Hu as demonstrated in Western blot. In immunohistochemical studies, the serum IgG immunostained neurons of the brains, spinal cords, and dorsal root ganglia of humans or rats. Confocal laser-scanning microscopy revealed binding of the patient's IgG in the neuronal nuclei and cytoplasm, but not in the nucleoli. In immunoelectron microscopic studies, immunolabelling with the IgG was found diffusely in the karyoplasm, excluding nucleoli, and in the cytoplasmic matrix between the cisternae of the reticulums, Golgi apparatus, and mitochondria. Encephalo-myeloganglionitis is a clinicopathological entity frequently associated with the presence of neoplasm and antineuronal antibody, however, the role of the antibody in the pathogenesis remains to be elucidated.