Neuroimmunology Testing

Neuropathies

Peripheral neuropathies, autoimmune responses of the peripheral nervous system, are associated with autoantibodies against various neural glycoconjugates. Neuropathies associated with anti-MAG with IgM paraproteinemia are often slowly progressive with evidence of demyelination and a variable degree of axonal loss associated with gait ataxia. 50% of all peripheral neuropathy cases with IgM paraproteinemia possess MAG antibodies. Detection of MAG autoantibodies is useful for the clinician, as it suggests active demyelination in a peripheral neuropathy.

Immunofluorescence is a sensitive method for the screening and detection of anti-nerve myelin associated proteins and ganglioside autoantibodies. Specimens found positive by immunofluorescence can be confirmed using the Western Blot method.

Paraneoplastic Syndromes

Autoimmune responses of the central nervous system, recognized as paraneoplastic neurologis disorders are manifestations of an antitumor immune response. The following autoantibodies are found in paraneoplastic syndromes:

Anti-Hu, type I anti-neuronal nuclear antibody (ANNA-1), is associated with small cell lung cancer resulting in paraneoplastic encephalomyelitis (PE).

Anti-Yo, anti-purkinje cell antibodies (PCA-1) is associated with ovarian and breast carcinomas resulting in paraneoplastic cerebellar degeneration (PCD).

Anti-Ri, type II anti-neuronal nuclear antibody (ANNA-2), is associated with neuroblastoma (children) and fallopian or breast cancer (adults) resulting in paraneoplasticopsoclonus myoclonus ataxia (POMA).

These markers help in discriminating between true paraneoplastic disorders and other inflammatory disorders of the nervous system that mimic a paraneoplastic syndrome. IFA provides a sensitive method of detecting these autoantibodies. Hu and Ri autoantibodies, which characteristically stain the granular cell nucleus, are easily distinguished from the Purkinjee cell cytoplasm staining Yo antibodies. Specimens found positive by IFA can be confirmed using the Western Blot method.